



■ •' ^ ■':! 


■ : •■ i' ^avj 



nvi^ to k^V)^^ 





' fe^^v*"^ LIBRARY OF CONGRESS. ' ^M^ '^ 



rS)V ^<^:^^i^^ Chai)._^__.. Copyrio-ht No. 

Slielf-..X5 













^' 




A TEXT BOOK 



PHYSICS OF AGRICULTURE 



BY 

R H. KING 

Professor of Agricultural Physics in tite University of Wisconsin 

Author of "The Soil;" "Irrigation and Drainage;" "Principles and 
Movements of Ground Water" 



Madison, Wis. 
PUHLISllKD BY THI-: AUTHOR 

1900 
All rights reserved 






.^'\ 



91150 



L.itDr««r> off Conn » ' *» » | 

DEC 201900 
SECOND COPY 

OdwwHl to 

ORDER DIVISION 

m: 24 1900 



COPYKIGHT, 1890 

«Y F. H. KING 



PREFACE. 



The great need of ai>rieii]tural practices at the present 
time is a keener a])preciation and a more thorough com- 
prehension of the principles which underlie them. The 
facts of agric\ilture are spread through so many and widely 
different fields, and are so numerous, that no one can hope 
to grasp them all or nee(1s to do so. But the laws and 
l^rinciples which control his ])ractice each farmer must 
know before he can secure his results with the greatest cer- 
tainty and at the least cost. 

In these ])ages the aim has been to present to the student 
who expects to be a farmer, some of the fundamental prin- 
ciples he must understand to become successful. They 
are presented from the standpoint of physics rather than 
of chemistry or of biology, and in dealing with the physical 
side of the problems the burden of effort has been to lead 
the student to see why he should practice ni<*re than 
WHAT^ and it is hoped the student will ]mrsue the vari<ms 
subjects treated in this spirit, not only in his study, but 
above all on the farm and in the field. 

The book in its present form is not complete in either of 
its sections, but lias been put together to meet the imme- 
diate needs of classes. 

F. H. King. 
University of Wisconsin, 

Madison, Wis., Dec. 5, 1900. 



CONTENTS. 



INTRODUCTION. 

PAGE. 

Matter and Force (j 

Mui.KcrLAK CoNSTlTrTJUX UK HnDlES 6 

I'istance between molecules, p. 7 ; Motions, p. 8 ; Size, p. 9 ; Rela- 
tion to fertilizers, p. 11 : to poisons, p. 12 : to odors, p. 13. 

IIciw Odous and Flavors Fixi> Their Way into Milk 14 

Enter cUu-ing secretion of milk, p. 14 ; Influenced by feed, p. 15 ; 
From the air. p. 15 ; Introduced with solids, p. 16 ; Developed 
after drawn, p. 16. 

Deodorizi.n'g ]Milk 16 

Method, p. 10 ; Place, p. 17 ; Cooling, p. 17. 

Work 18 

Energy 19 

Conservation, p. 19 : Source of the earth'^s energy, p. 20 ; Solar 
energy, p. 20 : How it reaches the earth, p. 21 ; Amount, p. 22 ; 
Rate of transmission, p. 23 ; Kinds of waves, p. 23 ; Evapora- 
tion of water, p. 24 ; Chemical changes produced, p. 24. 

Nature ov Heat and Cold 25 

Temferattre 25 

Measurement, p. '2'> ; Accuracy of thermometers, p. 26. 

Units of Work and KNER(iv 27 

Foot-pound and foot-ton, p. 27 ; Horse-power, p. 27 ; Unit of heat, 
p. 28. 

Specific and Latent HE.vr 29 

Melting of ice, p. 31 ; Evaporation of water, p. 31. 

PHYSICS OF THE SOIL. 
CHAPTER I. 

Nature. Origi.v and Waste of Soil. 

Soils and Subsoils 49 

Uses of Soil 50 

Formation of Soil 51 

Influence of rock texture, p. 51 ; Rock fissures, p. 53 ; Running 

water, p. .")4 ; Glaciers, p. 51 ; Humus soil. p. 61 ; Wind-formed, 

p. 03 ; Animals, p. 64. 



CHArTRU II. 

Chemical and Mi.xkkal Xatcke of Soils. 

PAGE. 

Essential CoNSTi'rrEXTS of a Fektile Soil 69 

Functions of E.ssential Plant Foods 70 

Chemical Cojiposition of Soils 71 

Difference between clayey and sandy, p. 71 : Differences due to 
texture, p. 72 ; Between soils and subsoils, p. 72 ; Between clay 
and liumus, p. IH : Between clay and loess, p. 73 ; Between 
arid and humid, j). 7."! : Ijctwecn soil and rock, p. 77. 

Humus ^ 7G 

Of arid and liumid climates, p. 70. 

Plant Food 79 

Amount removed from soil by crops, p. 7!) : Amount in soil, p. 79 : 
Number of crops produced, p. SO : Itotliamstead experiments, 
p. 81. 

Nitrogen ix the Sou 82 

Amount in Manitoba soils, p. S2 : Forms of occurrence, p. S3 ; Dis- 
tribution in soil, p. S?> : Amount as nitric acid, p. 84. 

Sources of Soil Nitkooex 85 

Of humic nitrogen, p. 8.5 : Symbiosis, p. 87 : Observations of Wino- 
gradsky and Berthelot. p. 88. 

Nitrification 89 

Denituificatio.n 89 



CHAPTER in. 

Soi.TBLE .Salts in Field Soils. 

Soluble Salts in Field Soils 92 

Amount, p. 92 ; Amount limiting plant growth, p. 93 : Mode of 
action on plants, p. !>;'>: Concentration in Zones, n. '.)4 : Origin, 
p. 94 ; In marsli soils, p. 95. 

Leaching Necessary to Fertile Soils 95 

Correction of alkali lands, p. 9.") : Drainage ultimate remedy, p. 98 ; 
Tillage helpful, p. 98. 

Changes in Amount of Solirle Salts 98 

With season, p. 98 ; with different crops, p. 99. 

Nitrates 101 

Relation to total salts, p. 101 : Closeness of plant feeding, p. 101 : 
Limits at whicli plants turn yellow, p. 102 ; In fallow and 
cropped ground, p. 103 ; Loss during winter, p. 104 ; Influenced 
by cultivation, p. 105. 

Physical Effects of Soluble Salts 106 

On movements of soil moisture, p. 106 ; On surface tension, p. 106 ; 
On evaporation, p. 106; On viscosity, p. 106. 



Vll 



ClIAl'TKlt IV. 
I'll vsicAi. Xatiuk ok Soil,. 

PAGM. 

Textikk of Sou los 

Size of soil i.'riiii!s. u. KiS; Sizi^ of soil l^eincls. n. no. 

Poke Si'aok ix Son Ill 

Determines ma.vimuni wafer capacity, p. 114: Intluences rate of 
percolation, p. lir> : Method nieasiiring. p. ]1.">: Lai-gest possi- 
ble, p. 116. 

Intkknai, SiKFArE OF Soils 118 

Amount per gram and s(|. ft., p. IIM: Iteterminatiim. p. 111). 

EFFECTIVIC DiAilETEK OF SoIL (JUAIN.S 121 

Method of determination, p. 121 ; Flow of fluids computed from, 
p. 128; surface computed from, p. 124. 
Wkioht <<v Soils 127 

fllAl'TKR V. 

Son. MoISIIHK. 

Conditions of Soil Moistuui: 129 

(iravitational, p. 129: Caiiillar.v. i:'.(i: Ilygroscoijic. p. i;'.o. 

Water Content of Soils 131 

Ways of expressing, p. l."5I : Ma.ximum capacity of tield soils, p. 
181: Capillary capacity, p. 1l!2: Influence of distance above 
standing water on capacity, p. 184. 

Soil, Moistt're Available to Cuoi's 185 

Soils which yield moisture most completely, p. 136 : Relation of 
thickness of moisture film to per cent, of water, p. 187 ; Af- 
fected by jointed structure, p. 188; Increased by open struc- 
ture, p. 188 : By drainage, p. 189. 

Amount of Water Recjuiked by Crops 139 

For different yields of wheat, p. 140 ; Least amount for different 
crops, p. 141. 

<'11A1'T1:R VI. 
I'HYsics OF PLA.xr Hkeathino a.\i> Root Action. 

Mechanis.m and Method of Transpiration 142 

Breathing of plants and animals, p. 142 : Respiratory organs in 
plants, p. 142: Breathing pores, p. 148: chlorophyll cells, p. 
148: (Juard cells, n. 14:'.: Their action, p. 144: Loss of water 
through, p. 14."i. 

Strih'TI'RE and Mode of Root .\ciion 145 

Functions of roots, ]). 14."): Absorbing portion, p. 146; structure 
of root hairs, p. 147 ; Relation to soil grains, p. 147 : Method of 
gathering water, p. 147: Advance through soil. i). 148; lOx- 
tent of root develoi)ment. \). ^7,(\ ; Total root of plants, p. 157. 



ClIAl'TKK VII. 

MiiVKMKNTS OF SoIL MoISTlIiK. 

PAGE. 
OltAVITATlUNAL MdVKME.N'TS 158 

I'erc-olation. p. 108 ; Rate through sand, p. 150 ; Through soli, p. 
150: Through dry soil. p. ItiO. 
Capillary Movements 161 

Kise in capillary tubes, p. Itil : Rise in soils, p. 163 ; Observed 
hight in moist soil, p. 165 : Measurement of maximum hight, 
p. 1(!7 : Rate of rise in wet soil. p. 168 ; In dry soil, p. 168 ; In- 
fluenced by rain, p. 170; By farmyard manure, p. 172; By 
mulches, p. 17.S ; By firming the soil, p. 174. 
Thermal Movement.s 175 

Hygroscopic soil moisture, p. 175; ^Movements, p. 175: Relation to 
size of soil grains, p. 176; Amount a soil may absorb, p. 178; 
Intei'nal evaiioi'athin. p. 170. 

CIIAl'TKR Till. 
<'(iNSKU\.\rio\ or Son. Moistiue. 

Modes of ('ontkoi.lixc Sou, ;\Ioi.stike 181 

Late fall plowing, p. ISl: I>ate tillage for orchards, p. 182: 
Early fall plowing, p. 182: Early spring plowing, p. 18.3: Ef- 
fectiveness of mulches, p. 185 : Frequency of cultivation, p. 
187: Cultivation after rains, p. 100; Depth of cultivation, p. 
101 : Depth and frequency vary with the season, p. 191 : 
Early harrowing of corn and potatoes, p. 102 : Harrowing and 
rolling small grain after it is up, p. 102 ; Mulches other than 
soil. p. 10.",. 

SiP.s.iii.!.\(; TO Save Moistfre 105 

Increases water capacity, p. 108 : decreases cai>illarity. p. 199 ; 
Favors percolation, p. 199 : More of water available, p. 200. 

Danger From Grekx Manfrixo 201 

Wind-Breaks and Hedges 202 

CIIAl'TER IX. 

Relation of Air to Soil. 

/ 

Needs of Soil Ventilation 204 

Needs of free oxygen, p. 204 : Fixing of free nitrogen, p. 206. 

Processes of Soil Ventilation 207 

By diffusion, p. 207 ; By changes of soil temperature, p. 207 : By 
changes of barometric pressure, p. 208 : By wind suction, p. 
208 : By rains, p. 209. 

Ways of I NFU'ENciNf; Soil Ventilation 2oo 

Modified by tillage, p. 209 ; Reduced bv rolling, p. 210 ; Increased 
by drainage, p. 210 ; Modified by vegetation, p. 211. 



tiiAi-ri:u X. 

Soil- 'ri:.MrKUA'rruii. 

PAGE. 

TK.Mi'KitATriiK AT Which (JiiDwrii ISkcins 212 

Best Soil Ti:.Mi'i:uATri;i; 212 

Influence on rate of germination, p. Iil4 ; Effect on root pressure, 
p. 215 : On the formation of nitrates. ii. -\'). 

("ONDITIOXS IXFLIEXCIXG Soil. TKMI'KKATfKK 215 

Speoiflc lieat of soil, p. 21") : Moisture in soil, p. 216 ; Color of soil, 
1). 217 : Topography, p. 218 : Texture of surface, p. 218 ; Tillage, 
p. 2r.t: Chemical changes, p. 219 : Uains and percolation, p. 
21'.> ; Uate of evaporation, p. 220. 
Mk ANS OF COXTKOI.LlXd SoiL Tempekatlre 221 

Kolling, p. 221 : Earl.v thorough tillage, p. 222 ; Thorough drainage, 
]). 222. 



(•1I.\1'T1:K XI. 
Oh.ikcts, Mi;rnoi>s ami I.mi'i.emexts of Tillage. 

()B.ii;(Ts OF Tii.la.;e 223 

Tillage to De.sthoy Weeds 223 

Best time, p. 224: Best tools, p. 22."! ; For early killing, p. 225; 
For intertillage, p. 22<). 

Tillage to Moiufy Textihe 231 

Soil texture and tilth, p. 2:'.l : Importance of good tilth, p. 233. 

IIo-\v Textuhe axi) Tilth are Devkloped 233 

The uses of harrows, p. 234; The planker, p. .236 ; The roller, p. 
237 ; The plow, p. 238 : How may puddle soil.s. p. 2:i!t ; May 
correct texture and improve tilth, p. 230. 



Forms of I' 



239 



Must be adapted to the soil. p. 24(t : Sod plow, p. 241 ; Pulverizing 
plow, 1). 242 : Mellow soil plow, p. 242. 

Draft of I'i.ows 243 

English and American trials, p. 243; Draft of sod plow with and 
without coulter, p. 243 ; Sod compared with stubble plow, p. 
::44 : influence of moisture on draft, p. 244 : Draft of sulky 
plow. p. 245 : Line of draft, p. 240 : Scouring of pJows, p. 247. 

Care of Plows 247 

When not in use. p. 247 : Keeping in form. p. 247. 

SiBSOiL Plow 250 

Ob.tegts, Methods axd Times of Plowixg 250 

Depth of plowing, p. 250 : Best condition of soil for, p. 251 ; Treat- 
ment after plowing, p. 252 ; Plowing for corn in the fall, p. 
252 : Plowing sod. p. 252 : Plowing under manure, p. 253 : Plow- 
ing under green manure, p. 25:? : Early fall plowing, p. 254. 



GROUND WATER, WELLS AND FARM DRAINAGE. 
CHAI'TKU XII. 

MdVKME.NTS OF GliOl .\1> W.VTKU. 

PAGE. 

AmoT'Nt SroiiKD IN (JiidiMi 2r>5 

Ground water surface, p. 258 : Seepage, p. 258 : (irowth of streams, 
p. 259 : Kise of ground water througli precipitation, i). 260 ; 
Law of flow tlirougli sands, p. 202 ; Calculation of flow, p. 202 : 
(Observed and computed flow. p. 204 ; Relation of rate of flow to 
diameter, p. 200 ; Relation of pressure to flow, p. 20() ; Observed 
rates of flow in sand and rock, j). 208 ; (leneral movements 
across wide areas, p. 270. 

Fluctuations in the Rate op Flow of Gkound Water 270 

Due to bai-ometric changes, p. 270 ; In springs, p. 270 : In rate of 
discharge from tile drains, p. 271 : Change of level in wells. i>. 
272; Due to changes in soil temperature, p. 271. 

CHAPTKR XITI. 

I'Aiur Wei.i.s. 

Essential Featiikes of a (Umd Well 275 

Capacity, p. 275 ; Best geological conditions, p. 27<! : Depth, p. 283. 

Conditions Influencino Cafacitv 270 

Size of grains and pore space, p. 270 ; Depth in water-bearing beds, 
p. 278 ; Pressure, p. 279 : Diameter of well. p. 279. 

Use of Sanu Stkaineus 281 

Capacity, p. 281 ; Compared with open well, p. 282. 

Temperature of Well Water 284 

Well Casing and Tor 284 

CllAI'TlOR XIV. 

PuiNriPLES OF FAinr Duai.nace. 

Necessity for Drainage 286 

Conditions Reqt'iring Dkai\a(;e 287 

Advantage of Drainage 287 

Increases root room, p. 287 : Increases available moisture, p. 288 : 
Makes soil warmer, p. 288; Better ventilation, p. 290. 

Tile Drai ns 290 

Essential features of drain tile, p. 291 ; IIow water enters tile, 
p. 292 ; Collars, p. 292 ; Depth laid. p. 292 : Distance between 
tile drains, p. 296. 

Conformation of Ground Water Anorr Drains 294 

Rise away from drains, p. 29:5 : Observed ground water surface, p. 
296; Rate of change of surface, p. 297. 



XI 



PAGE. 

MovK.MKST (ii- I <u.\i NAiJi-: WATint 208 

Heavy clay underlaid with sand. ii. 1!!)S : (iradienf. i). 2'JS ; Silt 
basin, p. 2!i!i : si>:e uf tile. p. 2!»!» : rractical illustration of sizes 
and leniiths. p. .•'.(M : Outlets, p. .■502: Joining laterals with 
mains, p. 'MV.i : OhstrucI ions. p. :'.():!. 

LAYIN<i OfT DUAINS .304 

SiikFACK DitAi NAci: 306 

("onstniction. p. :!(it; ; Inlerceptinj;- underflow, p. .".07: Itasins witli- 
ont outlets, p. :',0T. Lands leciuiiinir suiface drainajje, p. .S09. 



CIIAI'TIOK W. 

I'KArrrci-; of rMiKitniiAiNAcii:. 

Dktku.mininc; Lkvki.s 312 

Instruments, i). ."512: Metliod of leveling, ]>. :!1.S : Contour map. p. 
31.''): I.ocatinu: mains and laterals, p. :'i1.">: Uetermining grade, 
p. .'UT: ('hangiii.t;- frcun niic j;rade lo anothei'. ]i. 310. 

L>i(i(;iN(; THE Ditch 321 

Ditching tools, p. 321 : Width of ditch, p. 322 : Bringing bottom to 
grade, p. 322: I'lacing tile. p. 324: Filling the ditch, p. 328. 

RTT.1AL AROHITECTITRE. 

fHAI'TKR XVI. 

Stkength of Materials. 

5STKE.N(iTii OK Posts 329 

Stress, p. 329 : White pine pillars, p. 330. 

Transvekse Stuenoth 331 

Tensile streDSTth. o. 331 : Principles, u. :'.:'>1 : Proportional to 
squares of depth, p. 332 : Relation to length, p. 334 : Break- 
ing constants, p. 33.') : Computing loads, p. 336 ; Rafters, p. 
337 : Safe loads for horizontal beams, p. 337 ; Selection of lum- 
ber, p. 33S. 

Barn Frame.s 338 

Braces, p. 338: Constructing timbers from 2 inch lumber, p. 330: 
Forms of frames, p. 330; Plank frame, p. .'UO : Balloon frame, 
p. 340: Cylindrical frame, p. 341. 

ClIAPTKR XVII. 
Warmth. Light am. Ventilation. 



Control ov Tk.mi'Eratire 

Normal animal temperatures, p. 343 : Best stable temperature, p. 
344: Solid masonry walls, p. 346: Hollow masonry walls, p. 
347: Brick veneered walls, p. 347: All wood walls, p. 348. 



343 



PAGE. 

Lighting Faum Buildings ; 34g 

Efficiency of windows, p. :!4.S ; I'o.sitioii of windows, p. 349. 

Ventilation of Farm Buildings 350 

Necessity for ventilation, p. 350 ; Carbon dioxide, p. 350 ; Mois- 
tnre from lungs and skin. p. 350 ; Ammonia and organic mat- 
ter, p. 3.1J : Micro-organisms and dust. p. 352 : Bad ventila- 
tion predisposes to disease, p. '.','>'.'. 

Amount of Air Rrqi;ired 353 

Amount respired, p. 353 ; Degree of imiiurity permissible, p. 354 ; 
Rate of supply, p. 354. 

Construction of Ventilators 355 

Capacity of flues, p. 355 ; Forces producing ventilation, p. 358 ; es- 
sential features, p. 358 ; Location, p. 359 : Place of openings, p. 
360 : Introduction of fresh air, p. 362 ; Construction, p. 363 ; 
Ventilation of basement stables, p. 364. 



CHAPTER XVIir. 

Principles of Construction. 

Relation of Covering rt> Si-ace Enclosed 3<i6 

Relation of walls to floor space, p. 366 ; Relation of liight to ca- 
pacity, p. 367 ; Combined and separate construction, p. 370 : 
Saving of labor, p. 372. 

Stable Floors 374 

Essential features, p. ;!74 ; Cold and warm floors, p. 375 ; Use of 
bedding, j). 37(> ; Wood floors, p. 377 ; Making wood floors water- 
tight, p. 377 : Stone floors, p. 378 ; Macadam floors, p. 378 : 
Macadam for barn yard. p. 379. 

Construction of Cement Floors and Walks 379 

Kinds of cement, p. 379 ; Cement concrete, p. 379 ; Materials, 
p. 380 : Wetting crushed rock. p. 380 ; Ratio of ingredients for 
concrete, p. 381 : For finishing, p. 381 ; Thickness, p. 382 : 
Making and laying, p. 382. 

Cattle Ties 384 

Stanchions, p. 384: Adjustable stalls, p. 3S5 : Movable halter ties, 
p. 387. 

Mangers -"^SS 

Manure Drops 388 

Provisions for Watering 388 

Watering in bain, p. 388 ; Storing water in tanks, p. 389 ; Water- 
ing trough, p. 390. 
Arrangements for Fvloadini; Hay 391 

CHAPTER XIX. 

Construction of Silcs. 

CONDITION.S Essential for Preserving Silage 394 

Depth, p. 394 ; Rigid walls, p. 394 ; Protection against frost, p. 396. 



I'AOB. 

COXSTIUTTION nv SliiMO Sll.dS 397 

Laying walls, p. ;->y7 : I'lastering. p. 398 ; Doors, p. 399. 

COXSTIUTTION Ul'- Buit'K SlLOS 400 

Foundation, p. 400; Walls, p. 4(»2 : Tie-rods. p. 402: Making walls 
air-tight, p. 402 ; Uoors, p. 403. 

CoxsTinrTiox mf Bkick-Lixku Silos 40.3 

Foundation and sill, p. 405 ; Setting studding, p. 40.") : Slieeting, 
p. 40."> : Siding, p. 406 ; Lining, p. 40(i. 

Lathed axu I'lasteked Silos 407 

coxstrtctiox of all wood silos 409 

Foundation, p. 409 ; Cementing bottom, p. 410 ; Sills and studding, 
p. 410; Sheeting and siding, p. 412: Plate, p. 413; Lining, 
p. 41.'^: Ivoof, p. 417: "V'entilation, j). 417: Tainting lining, 
p. 4 IS. 

Stave or Taxk Silo 418 

Construction, p. 420 : Staves, p. 422 ; Foundation, p. 422 ; Hoops, 
p. 422 : Doors, p. 423. 

Pit Silo.s 423 

DiMENSiox OF Silos 424 

Weight of silage, p. 424: Capacity of silos, p. 424: Horizontal 
feeding area, p. 42.5. 
Daxoek IX Fn.i.ixi: Silos 427 



FARM MECHANICS. 

CHAPTER XX. 
Prixcii'LES of Kraft 428-443 

CHAPTKK XXI. 

CONSTRFC'TIOX AXD ^LilXTEXAXCE OP COUXTRY ROADS. 
RdAD 1 tRAIXAGE 445 

Texti're of Roaii Materiai, 450 

Earth Roads 452 

Stoxe Roads 461 

MAIXTEXANCK DF CofXTRV RO.VDS 480 

METEOROLOGY. 
CH.VPTKU XXII. 
TiiK Atmusfiieui:. 

Rki.atiun tu the IvutTii 48(; 

Interpenetration of the three spheres, p. 4.S7 : Relation of the life 
■ zone, p. 4S7. 



PAGE. 

ATMOSr-HKKE ^gf^ 

Depth, p. 48S : ("omposition, p. 4.S1I : Materials iiieehanieally sus- 
pended, p. 4.S!t. 

I'AKTS I'LAYED l;Y TIIK DlFFEIiK.N T I XCKKPIEXTS 489 

Oxygen, p. 48!): Nitrogen, p. 4!i(i : Water, p. 490; Dust, p. 490: 
Carlion dioxide, p. 4P0. 
ATMOSI'HKUIC I'KES.StRE 491 

Applications or pressure, p. 491. 
Temtekatihe of the AriKi.si'HEiiE 492 



CIIAI'TKK X.XIII. 

.MuVEMEXTS (IE THE At.M( tSI'UEHE. 

I'KI.MAIJV t'AlHE ()'■' WlXIiS 493 

GEiNEKAI. ClIfCTEATIOX OK THE AtJIOSPHEUE 494 

World system of winds, p. 494 : Wind zones, p. 49.5 : Direction af- 
fected by form and rotation of tlie eartli, i). 496 : Character of 
the winds, p. 496 : Weather of the wind zones, p. 497 : Shift- 
ing of the zones, p. 497. 
Continental Wi.xds 498 

Influence of continents on winds, p. 498 : Winds of .Tanuary. p. 
499: Winds of .Julv. ii. 4!>'.> : Mi)nsoons, p. .")02. 
( )iiiii xauy Si < iiiM.s .">02 

Cyclones, p. ')0'2 : Cause of wind directions, p. ."02 : Progressive 
movements, p. 504 : Direction of movement, i). 506 ; Rate of 
progress, p. 506: Diameters, p. 506 : Duration, p. 507: Region 
of precipitation, p. 507: Origin, j). 508. 



ciiAi'Tin: \\n'. 

Weaiheh Chaxiies. 

PBINCIPEES (IF F(IHE('ASTTN(J WEATHEI! CHAX(iES 510 

I'revailing winds of locality, p. 510: I>ocating storm center, p. 
511 : Change of wind direction, p. 511 ; Direction of storm cen- 
ter, p. 511 : Predicting the course of tlie storm track, p. 512 : 
Temperature changes, p. 512 : Barometric cliaufres. p. 514. 

COI-P WEAVES 514 

Forecasting warm and cold weather, ]>. 515. 

I.oNf; Warm and Ditv PEUTdps 515 

Tropicae Cyclones •''>17 

Thunder Storms. Hail Stukms axk T()i;x\p(ies 518 

Relations to ordinary storms, p. 518: Tornaoops. p. 518; Schools 
of tornadoes, p. 520 : Distribution of thunder showers, p. 520 : 
Conditions of formation, p. 520 ; Formation of tornadoes, p. 
521 : Explosive violence of tornadoes, p. 522 : Unsteady move- 
ment, p. 523 : Character of tornado path. p. 523 : Formation of 
thunder showers, p. 524 ; Formation of hail, p. 524. 



INTRODUCTION. 



1. Physics. — Briefly defined, pliysies is tlie science of 
^latfer and Energy. It aims to nieasnre and investigate 
the movements of or within any body, whether living or 
dead, endeavoring to show how the forces of nature operate 
upon or wifhin the hody to produce the phenomena associ- 
ated with it. 

If we were endeavoring to ascertain how much the sun 
weighs, how much energy in the form of heat and light is 
being sent out from it daily, or how this energy is pro- 
duced, our study would be one of Solar Pliijsics. If we 
were measuring the diameter of the earth, or the volume 
of water in the oceans ; if we were endeavoring to ascertain 
how the forces have operated to uplift mountain ranges or 
to cut out deep canons or broad valleys, then our problem 
would be one of Tevvestrial or Earth Physics. If we were 
measuring the strength of a horse ; how many ]iounds of 
feed he must use to plow 10 acres of ground ; or endeavor- 
ing to show how the oxygen he breathes and the food he eats 
give rise to the energy of his muscles, our problem woidd 
be one of Animal Physics. If we were studying how the 
root forces its way through the soil ; how water is forced 
into and through the roots to the leaves on the tree or how 
the sunshine breaks down the carbon dioxide in fhe green 
<'hloro])hyll, onr ])roblem would become one of Plant Phjjs- 
vrx. If we are endeavoring to determine the dimensions 
of beams to use in a barn ; how heavy a rod to use in a truss 
or how to brace a building so that it may safely withstand 
the pressure of the wind, then we are dealing with the 
PJn/strs of Avcliilcclure. And so we might go on enumer- 



ating every science and every art to show that there is a 
physics of each or a necessary treatment of them from the 
standiDoint of mechanical principles of matter and energy. 
Physics, therefore, a broad science, is one of wide applica- 
tion and fundamentally imjwrtant to the nnderstanding of 
almost any concrete snbject when treated from the stand- 
point of cause and effect. 

2. Matter and Force. — So far as we are at present able 
to comprehend, the various phenomena of nature are mani- 
festations of two classes of agencies, matter and force. The 
river flowing steadily toward the sea is a mass of matter 
urged continually onward by the force of gravitation. Coal 
and oxygen burning in the firebox of the locomotive are two 
forms of matter urged into motion by the force chemical 
affinity. The time-keeping watch is a mechanism of brass 
and steel kept in uniform motion by the force cohesion un- 
coiling the wound-up spring; and the capillary rise of oil 
in the lamp wick and of water through the soil are other 
movements of matter actuated by the same force. 

3. Constitution of Bodies. — AH bodies or masses of mat- 
ter with which we are acquainted possess such properties 
as to make it appear that there is room in them not occu- 
pied by the essential material which makes up the body. 
They are made out of definite units which have been 
named molecules much as a bank of sand is composed of 
:grains or as a sack of shot is filled with spheres of lead. 

The openness of structure of all bodies is a very impor- 
tant conception to have clearly in mind. It is this open- 
ness of structure which makes it possible for foul odors 
to be absorbed by milk or drinking water ; for moisture 
to enter sprouting seeds ; for the food we eat to pass through 
the walls of the alimentary canal to enter the blood vessels 
and out of these again to the muscles and nerve centers. 
It is the openness of structure of the lung lining which per- 
mits the oxygen of the air to enter the system and the car- 
bonic oxide to escape from it ; and were it not for this struc- 



ture we could neither smell nor taste, for substances must 
penetrate these sense organs before the sensations are 
awakened. 

That there is unoccupied space in bodies which appear 
to have a close structure may be demonstrated with the ap- 
paratus represented in Fig. 1. The bottle is 
filled with water and into this is dropped a 
large crystal of some salt, as potassium ni- 
trate or sulfate, or 4 teaspoonfuls of granu- 
lated sugar. AVlien this is done the rubl)er 
cork carrying the graduated glass tube is in- 
serted and crowded down until the water 
rises in the tube and stands at one of the 
graduation marks. If any change in volume 
occurs with the solution of the salt it will be 
shown by a rise or fall of the water in the 
tnbe where the amount of change can be read. 
The bottle is ])laced in a large vessel of 
water for the purpose of maintaining a con- 
stant temperature during the experiment. 

The molecules themselves are made up of 
smaller nnits which have received the name 
of atoms and the number of these atoms 
which enter into the construction of the molecule varies 
with the substance. In some substances the molecule con- 
sists of two atoms, as common salt, one of sodium and one 
of chlorine, while the water molecule contains three atoms, 
two of hydrogen and one of oxygen. In molecules of cane 
sugar there are forty-live atoms of three different kinds, 
carbon, hydrogen and oxygen, and there are many sub- 
stances having molecules more complex than those of sugar. 




Fig 



4. Distances Between Molecules Change With the Tem- 
perature of the Body. — A bar of iron lengthens and shortens 
as its temperature rises and falls, and the wheelwright 
takes advantage of the fact to set the tires of the wagon. 
This change of volume with temperature is due to the fact 
that the mean distance between the molecules becomes 



greater the higher and less the h^wer the temperature is. 
From this it follows that ordinarily molecules are not in 
contact and that there is room in the interior of bodies, 
however compact they appear to be, not occupied by them. 
Observations with the ordinary mercurial thermometer 
prove the same general fact. As the temperature rises 
a portion of the mercury is forced out of the bulb into the 
stem showing that there is not room enough there for all 
of the mercury although the bulb has actually become 
larger. So, too, when the temperature falls the mercury 
again returns to the bulb altliough the bulb has itself be- 
come smaller than before. 

5. Molecules of Bodies Always in Motion. — It follows 
from what has been said in the last section that with every 
change of temperature in bodies their molecules move. 
The general fact is that the molecules of all bodies whose 
temperature is not absolute zero are in rapid motion no 
matter whether the body be a solid, a liquid or a gas. The 
higher the temperature of the body the more rapidly do 
the molecules in it vibrate, the greater is their rebound 
after each collision and so the greater is the mean distance 
between them ; this is why most bodies expand with in- 
crease of temperature and contract Avhen cooling. 

It is the fact of movement among molecules which 
causes the diffusion of sugar or salt through water after 
solution takes place, which causes the perfume of flowers 
to be constantly moving away from them, which gives solid 
camphor its odor and which causes snow and ice to evapo- 
rate at temperatures even below freezing. 

The elastic power of air in the bicycle tire is due to the 
rapid movement of the molecules and their frequent and 
hard collision against the walls. It is the same fact which 
gives the steam its power to drive the engine. The larger 
the amount of air which is pumped into the tire of the 
bicycle the greater is the number of collisions per square 
inch of surface per second and so the harder the tire be- 
comes. Then, again, when the wheel is left in the hot 



9 

sun the greater tension which is (h'veloped is due to the 
fact that the alisorption of heat causes ail the niok'cules 
to travel faster, and, traveling- faster, they must exert a 
greater pressure whenever collision occurs and tlieir motion 
is arrested. 

It has been computed that tlie mean rate at which the 
molecules of hydrogen gas travel at ordinary temperature 
and atmospheric jDressure is some (3,000 feet per second. 
Under the same conditions molecules of oxygen gas which 
are 16 times as heavy travel only one-fourth as rapidly. 

If it is difficult to think of a body like a horse-shoe or 
a hanuner maintaining its form against great strains when 
the molecules composing it are neither at rest nor in con- 
tact it may be helpful to recall the conditions which exist 
in the solar system. Here we have the sun with all its 
planets and their satellites, together with asteroids, comets 
and meteors, each in rapid motion but separated by im- 
mense distances, and yet the whole system constitutes one 
gigantic body maintaining persistently its form as it moves 
through space. 

6. The Size of Molecules. — ]\Ioleeul>'s are so very small 
that it is extremely difficult to form any just conception 
of them, yet there are many experiments and observations 
which prove them very minute. Xobert, for example, 
ruled parallel lines on glass at the rate of 101,000 per 
linear inch, })roving that the point of the diamond which 
jDlowed the furrows must have l)een far less than tdcVoij of 
an inch in diameter. 

Lord Kelvin has computed that the number of molecules 
in a cubic inch of any perfect gas under a temperature 
of 32° F. and a pressure of 30 inches of mercury must be 
as great as 10^^ or ten sextillions. 

This is an enormous number, but that there is a proba- 
bility of truth in it may be demonstrated by a simple ex- 
periment. 

Dissolve .05 of a gram of analine violet in alcohol and 
distribute it through 500 cu. in. of water in a large glass 



10 

flask. Pom- out half the colored water and fill to 500 
cu. in. again. Eepeat this operation as long as the eye 
can with certainty detect the color in the water. As many 
as nine divisions may be made and the eye detect the color 
Mdien looking down through 12 inches of the water poured 
into a long glass tube held over white paper, using a sim- 
ilar tube with clear water as a standard for comparison. 

If the division of the analine is carried to this extent 
there will bo in the last 500 cubic inches of water only 

5J2 of Jqq = iQ 240 ^^ ^ gram of analine. 

It is reasonable to suppose that in the last 500 cubic 
inches of water there was at least one molecule of analine 
in each cube of water .01 of an inch on a side, and if this 
is true there must have been at least 

100 X 100 X 100 X 500 =3 500,000,000 

molecules of analine in the last vessel of w^ater. Since at 
least this number of molecules is found in TXiho of a 
gram of analine one gram would contain not less than 

10, 240 X 500, 000, 000 = 5, 120, 000, 000, 000 molecules. 

It is plain, therefore, from this straightforward line of 
observation and simple calculation that molecules of ana- 
line at least must be very small and that a pound of the 
material would contain an enormous nund)er. 

From another line of observation Maxwell has computed 
that the molecules of hydrogen, oxygen and carbon dioxide 
are so small that the numbers in the tal)lo below are re- 
quired to weigh one gram. 

jSTumber of molecules in one gram of 

Hydrogen Oxygen Carbon dioxide 

2,171(10)='^ 1,359(10)2 2 9,881(10)2 1 

That is to say, the number of molec\iles is so large in one 
gram of these three substances that 2,171, 1,359 and 9,881 



11 

must be multiplied hy 10 used as a factor 23, 22 and 21 
times respectively in order to express them. 

7. Molecules and Commercial Fertilizers. — It is a very 
strimge fact that iUU to 501) pounds of commercial fertil- 
izers applied to a poor soil will produce such marked ef- 
fects upon the growth of plants when these small amounts 
are spread over an acre of ground and then dissolved in 
and distributed tlir(iugh the soil water of perhaps the en- 
tire surface four feet. To know, however, that the mole- 
cules of these fertilizers are so extremely small and that 
there are such immense numbers of them in a single pound 
enables the mind to better comprehend how such marked 
eifects are possible. 

The surface four feet of good field soil when well supplied 
with moisture may contain the equivalent of 10 inches of 
water on the level. This amount of water expressed in 
cubic feet per acre is 30,300. The experiment Avith an- 
aline indicates that a single gram has been divided into not 
less than 5,120,000,000,000 parts. Let us compute how 
many parts this number would give to each cubic inch of 
the 36,300 cubic feet of soil- water in the upper four feet 
of an acre. 

5, 1-20, 000^00^000 _ 
""36,300X1,728 " «' ' '^^^ 

We see, then, that a single gram of analine may be di- 
vided enough to place 81,624 parts in every cubic inch of 
moisture of an entire acre of good soil to a depth of four 
feet. 

But one gram of sodium nitrate would contain, accord- 
ing to Maxwell's results, 

NaNOg :2 O :: No. of O molecules : No. of NaNOg molecules 
or 85:32 :: 1,359(10)" ; x 

whence x = 51(10)-» ^5,100,000,000,000,000,000,000,000 



12 

Treating this result as we did tliat of the aiialine wo shall 
have 

5, 100, 000, 000, 000, 000, 000, 000, 000 „, 

ofi onn ./ 1 U -^ = 81,310,000,000,000,000 

as the numher of molecules of sodium nitrate in each cubic 
inch of water from which the plants may draw their sup- 
ply of nitrogen. It will be seeu that this number is so 
large that even a cube of water .01 inch on a side will 
contain 81,310,000,000, a number far too large for com- 
prehension, and yet if 200 pounds of sodium nitrate were 
applied to the acre this number would have to be multiplied 
by the number of grams in 200 pounds to express the num- 
ber of molecules there would be for each cube of soil-water 
onediundredth of an inch on a side. 

8. Molecular Structure in Relation to Poisons. — It is the 

extremely large nundjer of molecules which may exist in a 
small space, coupled with the energy which these molecules 
may carry wdth them in their movements, which makes 
possible the violent disturbances in the life processes of 
animals and plants associated with the introduction into 
the system of such small quantities of substances known as 
poisons. It will be easily understood from what has been 
said regarding the vast number of fertilizer molecules per 
cubic inch of soil moisture, when oidy a single gram has 
been disseminated throughout the surface four feet of a 
full acre, that extremely small quantities of any poison, 
like strychnine, will contain molecides enough to charge, 
the body of the largest animal with) great numbers of the 
poisonous units. 

The important i)ractical lesson t<;> be remendjered in 
this connection is that, since such extremely small quan- 
tities of matter, when introduced into the plant or animal 
body, are sometimes capable of producing such profound 
disturbances as to cause death, extremely small quantities 
of other substances may have very important beneficial 
effects ; and it is quite possible that it may be along such 



13 

lines as these we must search fur an exphuiation of soniG 
of the little understood points associated with the nourish- 
ment of both plants and animals. 

9. Ability to Recognize Small Quantities of Matter. — We 

often marvel at the (h'licacv of the chemical l)ahince and 
many other instruments of measurement, hut the delicacy 
of the sense organs of men and animals, and particularly 
the sense of smell, is so extreme that it is difficult to form 
a just conception of the minuteness of the quantity 
of matter or of energy to which they will respond with the 
degree of intensity which permits accurate judgments to 
he formed. 

The sensations of odors result from the disturbances 
jjroduced on the organs of smell by molecules of different 
substances moving through the air when brought to the 
nose. But Avhen the blind lady took the glove of a stranger 
and, walking up and down the aisles of a large audience 
room filled with ]ieo]ile, handed the glove to the owner, 
made known to her only by the likeness of the odor from 
the glove to that escajiing from the* stranger, who will say 
what fraction of a gram of that volatile principle it was 
which produced so marked a sensation \ The weight of 
volatile substance rising into the air from a man's track, 
made by a shoe rather than his bare foot, must be very 
small indeed, and yet the sense of smell in the dog is 
so keen that he will follow his master at a rapid run even 
when the tracks are two hours old and where many other 
peojde may have passed along the same course more re- 
cently than did his master. 

The readiness with which flow^ers, fruits and vegetables 
may be identified by their odors alone, often at consider- 
able distances, and with which animals scent their enemies 
or their food, are all of them concrete demonstrations at 
once of the extreme minuteness and vast nundjors of mole- 
cules, while at the same time they prove how sensitive is 
the animal organization to such minute quantities of ma- 
terial. 



14 

10. Foul Odors and Flavors in Dairy Products. — Since the 
commercial value of dairy products is determined in a 
high degree by their flavors and odors and since these 
qualities are judged through the sense of smell, which we 
have seen is so extremely delicate and keen, and since such 
minute quantities of the odor or flavor j)i*otlucing sub- 
stances are certain to awaken the undesirable impressions,, 
it is clear that the greatest of care must be exercised in 
l>roducing, handling and caring for them through all the 
steps preceding the delivery to the consumer. Since we 
have seen that so little fertilizer may be disseminated 
through so much soil moisture and since so little may be de- 
tected by the organs of smell, it is 2>lain that too great care 
cannot be taken in keeping the milk clean and that only 
those who do this can hope to secure the custom of people 
willing to pay a high ju-ice for the milk, cream, butter or 
cheese which just suits them. 

11. How Odors and Flavors Find Their Way Into Milk. — • 

The substances producing these qualities in milk make 
their entrance there in three different ways : ( 1 ) from the 
blood at the time the milk is secreted ; ( 2 ) from the outside 
after the milk is drawn ; and (3) they are produced within 
the milk after it has been secreted before or after it is 
drawn. 

12. Odors Entering Milk During Secretion. — Auv volatile 
principle Avhicli may chance to be present in the blood of 
the animal at the time the milk is being drawn will find 
its way into the milk and will impart a quality to it, the 
intensity of the flavor or odor depending upon the amount 
of the volatile principle present and the readiness with 
which it evaporates. 

N^early all food stuffs contain substances which produce 
odors and if these substances are not destroyed during the 
processes of digestion they will again escape from the body 
of the animal through the channels of excretion ; that is, 
through the skin, kidneys, lungs, rectum or udder, and if 



15 

any of these priiiei])les still reiuain in the blood at the 
time the milk is being drawn they will appear in it. It 
follows, therefore, that the longer the interval of time be- 
tween the taking of food into the body and the drawing 
of the milk the less danger there will be of the milk be^ 
ing tainted by it. The reason for this is fonnd in the fact 
that the milk is excreted during the time of milking while 
the blood is coursing through the udder, carrying whatever 
odor producing substances may then be present. 

13. Time to Feed Odor Producing Foods. — It is clear from 
what has been said that if it is desired not to have the 
milk charged with the undigestible odor-principles of food 
while it is being drawn these foods should be fed as soon 
as possible after milking and never just before in order 
that time enough may have elapsed to permit the odor 
principles to have been eliminated from the blood by the 
other organs. On the other hand, if the food contains a 
principle whose odor is desired in the milk, then the re- 
verse rule as regards time of feeding should be practiced, 
namely, to feed these just before milking. 

14. Introduction of Odors Into Milk From the Air. — It is 
the fact that the molecules of substances are not in contact 
and that they are in motion which makes it possible for 
milk Avlien in an atmosphere containing odors to become 
charged with them. If the odors of manure, of urine, 
of ammonia, or any of those associated with the decay 
of organic matter are in the air above the milk the rapid 
motion of these molecules will cause some of them to 
plunge into the milk and accumulate there until they be- 
come so numerous that just as many tend to escape per 
minute as tend to enter. The milk is then saturated with 
the odor in question. 

The warmer the air surrounding the milk and the 
warmer the milk the more quickly will the condition of 



16 

saturation be readied, simply Lecause the rapidity of mo- 
lecular motion increases with the temperature, for when 
the molecules of foul odor are once inside the warm milk 
they travel or diffuse downward more rapidly because it 
is warm. 

15. Odors and Flavors Eesulting From the Introduction of 
Solids Into Milk. — It must be clear from what was demon- 
strated in (6) that when great care is not taken both in 
keeping the stable and cows clean and free from dust the 
fine particles of dirt falling into the milk, even though 
the amount is small, may readily dissolve and impart a 
strong flavor to it, and one careless milker may easily 
greatly injure the quality of that from the whole herd 
where all of the milk is pooled. The fundamental point to 
be kept ever in mind is that a very little dirt is capable 
of being divided to an extreme degree and that through 
the senses of taste and smell extremely small amounts may 
readily be detected. 

16. Odors and Flavors Developed in Milk After It is 
Drawn. — Milk is a very nutritive fluid and for this rea- 
son great care must be exercised not only to keep dirt out 
but also to prevent those germs from entering it which 
have the power of developing rapidly there, producing un- 
desirable odors and flavors and thus injuring the quality 
of the milk. These objectionable germs are liable to be 
introduced into the milk through the dust from the sta- 
ble and the cow as well as from the lack of proper cleanli- 
ness of the vessels in which the milk is handled. 

17. Deodorizing Milk. — The removal of odors from milk 
may be accomplished by greatly increasing its surface in 
a space containing none of the odors which the milk con- 
tains. The method known as the "Aeration of Milk" has 
for its purpose this rather than the exposure of the milk 
to the air, as the presence of the air hinders the escape of 



17 

the (i(l(irs rather than favors it and if the milk coukl be ex- 
])osc(.l in a vacnuin tlieir escape Avouhl be more e<:)mplete and 
more rapid. 

The escape of the odors from the milk depends upon tho 
rapid motion of the odor molecules in it which forces them 
to escape whenever they approach the surface with sufti- 
cient velocity to overcome the surface attraction, and the 
division of the milk into a large number of small streams 
increases the chances for the odors to escape in proportion 
to the increase of the surface. The finer the milk streams, 
the farther thev are apart and the longer the stream is in 
falling- the more complete will the removal of the odors 
be. Where there can be a movement of air over the milk 
surface or among the streams of milk this will favor the 
removal by carrying the odor molecules away and thus 
preventing them from re-entering the streams. 

Since the molecidar movement is greater the higher the 
temperature it follows that the deodorizing process shotdd 
be applied as soon after the drawing of the milk as possi- 
ble before it has had time to cool and the molecular motion 
to slow down. 

18. Place For Using the Deodorizer. — If the aerator or 
deodorizer is used in the barn oi- where there are many ob- 
jectionable odors it must bo remembered that exactly the 
same conditions which favor the escape of the odors which 
the milk contains when drawn are the best conditions to 
permit it to becoino charged with odors from outside, and 
hence the deodorizer or aerator should be placed where it 
is surrounded by a current of ])ure air. 

19. Cooling Milk. — The cooling of milk innnediately 
after it is drawn has a ])owerful influence in preventing 
odors from develoi)ing in it as a result of the growth of 
any germs which may have found their way into the milk 
because the low temperature makes their growth much 
slower. Cooling, then, is not a deodorizing process but 
one which prevents the formation of new odors. If, then, 



18 

it is desired to remove tli/e animal odors this if possible 
should be done first and then the milk cooled to prevent 
the formation of other odors. 

20. Work. — Whenever any body is moved under the ac- 
tion of a force work is done and the amount of this work 
is measured by the intensity of the force and the distance 
through which it has acted. When a body weighing one 
pound is lifted one foot against the attraction of the earth 
the amount of work done is one foot-j)ound. The same 
weight lifted 10 feet represents 10 foot-pounds and 10 
pounds raised one foot has the same value. 

A team hauling a load over a road under a mean pull 
of 200 pounds is doing 200 foot-pounds of effective work 
for every foot traveled and in traveling 10 miles the total 
work done is 

10 X 5,280 X 200= 10,560,000 foot-pounds. 

Wlien a larger iniit than the foot-pound is desired that of 
the foot-ton may be employed and its value is 2,000 pounds 
lifted one foot high or 2,000 foot-pounds. If a wagon 
with its load weighing 4,000 pounds is moved along the 
road the work done Avill not be measured by the product 
of the load into the distance traveled but by the intensity 
of the pull necessary to pull the load into the distance trav- 
eled. On a good level macadam road 60 pounds will move 
a ton and 120 pounds two tons. To draw four tons over 
10 miles of such level road means the doing of 

4X60X10X5,280 _ „__ , . , 
9~?jm ^^ ' root-tons. 

So, too, if the pressure of steam on the head of tlie piston 
in a steam engine is 80 pounds per square inch and the 
area of the piston is 100 square inches the amount of work 
it can do per foot of stroke is 

80 X 100 = 8,000 foot-pounds. 



19 

If this engine makes 200 strokes per minute, then the work 
it does per minute will be 

200 X 8,000 = 1,600,000 foot-pounds. 

21. Energy. — Energy is the ability of a moving body to 
do work and the amount of energy the moving body has 
is measured by the amount of work it ean be made to do 
in coming to rest. If a weight suspended from a string 
be dra^m to one side and then released it will begin fall- 
ing and acquiring velocity, and on reaching the lowest 
level it will possess the ability of doing a certain amount 
of work. That amount will be enough to raise its own 
weight through the height from which it fell in the same 
time. If a bow is bent and the string is released against 
the arrow it will recover its form of rest but in doing so 
will imj^art to the arrow an amount of motion equal to that 
which the bow acquired in straightening out. When 
work is done in winding the clock the distorted spring 
has the power to develop an amount of energy equal to 
that expended in Avinding it up. In chopping wood the 
action of the woodsman's muscles increases the amount 
of motion in the ax until it falls upon the wood, when the 
energy which has been imparted to it does the work of cut- 
ting. 

"We cannot exert pressure enough wath the hand alone 
to force the nail into the board, but by giving the muscles 
an opportunity to act gradually upon the hammer it is 
a simple matter to store in it enough energy to easily drive 
the nail into the wood. W^hen coal or wood is burned in 
the fire-box of the engine and the heat developed converts 
water into steam under high pressure in the boiler we have 
still another case where energy is developed and accumu- 
lated in the rapidly moving molecules of steam Avhich drive 
the ])iston whenever the valves are opened holding to it. 

22. Conservation of Energy. — Xo discovery of modern 
science is more fundamental than the fact that neither mat- 
ter nor enerc'v can be destroved or created. One form 



20 

of energy may be transformed into another, and one kind 
of snbstance may be decomposed and others made from the 
components, bnt in these transformations there is neither 
annihilation nor creation. The small amount of ashes 
left from the winter's snpply of coal or wood seems to 
point to a destrnction of matter, bnt their Aveight added 
to that of the products which pass np the chimney is even 
greater than that of the original fnel by the amonnt of oxy- 
gen which was required to bnrn the fnel. So, too, the 
energy of 10 horses expended in threshing grain seems 
to be annihilated bnt it is only transformed. Heat of fric- 
tion and concussion, sound and material raised into new 
positions, from which it may fall, when added together will 
make a sum equal to that develoned by the horses. Again 
we appear to realize in the increase of our domestic ani- 
mals or in milk jn-oduced much less weight than has been 
used by them in feed and drink but this is because such 
large quantities of the materials eaten, breathed and drank 
escape in an invisible form through the skin and lungs. 

23. The Source of the Earth's Energy. — Tlie real source 
of the eartli's energy is the sun. All the rivers of the 
world flowing to the sea and the rush of the winds swaying 
the tree-tops and lashing the ocean into billows represent 
so much water and air lifted from a lower to- a higher level 
by the sun's heat and now being pulled hy gravity back 
to their original level to be raised again and to again re- 
turn, just as a pendulum rises and falls wdiile swinging 
through its arc. 

The wood burned in the stove, the coal burned in the en- 
gine and the food consumed by the horse are all the prod- 
uct of sunshine which lifted the constituents of soil, 
moisture and air into such condiinations as readily per- 
mits of their return to other forms, setting free the energy 
M-hich was consumed in producing them. 

24. Solar Energy. — When the sun rises the temperature 
increases, usually l)ecoming higher and higlier until past 



21 

noon, then when the sun sets the teni})erature falls again, 
continuing to do so until once more the sun is above the 
horizon. So, too, as our days grow longer and longer with 
the approach of sunnuer in the middle and higher lati- 
tudes, making more hours of sunshine in every twenty- 
four, the mean daily temperature increases but falls away 
again when the nights became longer than the days. Such 
and many other facts prove the sun to be a source of 
energy which in some manner is being transferred to our 
earth. More than this, since the earth travels entirely 
around the sun once each year and yet each day receives 
heat and light from it, it follows that solar energy is con- 
tinually leaving the sun in all directions, so that the 
amount arrested by the earth forms a very small portion 
of the whole. 

25. How Solar Energy Reaches the Earth. — To under- 
stand how the energy of the sun reaches us, coming across 
J>3,000,000 of miles we must learn that the energy travels 
in the form of waves through some medium filling space, 
which has been named ether, but whose real nature is not 
yet understood. 

Something similar to the process in question would be 
represented by a man at the center of a pond throwing 
its water into waves. These waves would spread in all 
directions and when reaching the beach a portion of the 
energy of the waves would be absorbed or transferred to 
whatever body they chanced to strike. The energy, 
therefore, generated in the muscles, is changed first into 
wave energy in the water and conveyed away from the 
man in all directions, but afterward when arrested at the 
beach, the waves may move the pebbles, making them 
grind upon one another, wearing themselves into sand, 
or their sliding may change a portion of the wave energy 
inio heat and thus the person in a small degree may warm 
the pebbles lying on the distant margin of the lake, not di- 
rectly by the heat of his body, but by the waves set up in 
2 



22 



the water, and much as the earth is warmed by waves sent 
out through the ether of space from the surface of the sun. 
The rapid and intense molecular motion at the surface 
of the sun is transformed into wave motions in the sur- 
rounding ether of space, as the motions of the imaginary 
man were changed into waves in the water, and these ether 
waves travel away from the sun's surface in all directions 
at the rate of 18(3,680 miles per second. So many of these 
waves as the size of the earth permits it to stop are arrested 
and transformed into the various forms of motion which 
are manifested at its surface. 

26. Amount of Energy Developed at the Sun's Surface. — • 

Careful measurements and calculations have shown that 
the energy developed second by second at the sun's surface, 
amounts, according to Lord Kelvin, to not less than 
133,000 horse power on each square meter or 1.09 square 
yards of its surface. 



27. Rate at Which Solar Energy Reaches the Earth's 
Surface. — As the intense energy developed at the surface of 
the sun spreads away from it, it becomes weaker and 
weaker in the ratio that the square of the distance of the 
waves from the sun increases, as represented in Fig. 2, and 




so at the earth's surface the amount of energy has become 
so much reduced that Lord Kelvin places it at only a little 
more than 1.3 horse power 2>er eacli square yard of surface. 



23 

But small as this amount of energy is when compared with 
that leaving a like area at the sun's surface it is neverthe- 
less very large. 

It may seem strange that so much energy falling upon 
the earth does not keep its surface at a higher temperature 
than is ohserved, hut when it is stated that the temperature 
of the space which surrounds the earth outside its atmos- 
phere is — 273" C. and that only the thin atmosphere 
shields the surface from this intense cold, it is plain that a 
large amount of heat must be required to hold the mean 
temperature even as high as 45° F. which is 

273' + 7° = 280° C above absolute zero. 

If we add to the necessity of holding the earth's surface at 
a temperature 280° C. to 300° 0. above the space in which 
it moves, the demand for energy needed to maintain the 
movements of water and of Avinds, together with that em- 
bodied in activities of animal and plant life, then 1.3 horse 
power per square yard of surface does not appear so much 
too large. 

28. Kinds of Ether Waves. — The energy reaching the 
earth from the sun in the form of wave motion is not all 
alike in that the waves have ditferent lengths, or, what is 
the same thing, greater numbers of one kind reach the 
earth in a unit of time. Waves which are so frequent that 
from 392 to 757 billions reach us per second produce the 
sensation of light when falling upon the eye; the slower 
ones producing red light and the more rapid ones the ex- 
treme violet colors of the rainbow. Associated with these 
oolor waves there are many other dark waves to which the 
human eye is not sensitive. Some of these are much 
shorter than the color wav(>s and are especially powerfnl 
in breaking down the molecular structure of ditferent sub- 
stances; that is, in ]iro(lucing cliemical changes such as oc- 
cur on the photographer's plate when the negative is made 
and such as take ])lace in the green parts of plants when car- 



24 

bon dioxide is broken down and the chemical changes are 
produced which result in building the sugars, starches and 
cellulose of plants. Others of these waves are much longer 
than the light waves and these have a wonderful power in 
producing heating effects when they fall upon certain sub- 
stances, one of which is w^ater. 

When bright sunshine is allowed to pass through a 
large lens the glass is but little w'armed by the passage, 
but if paper is held at the light focus it is quickly set on 
fire by the dark or invisible rays. That it is the dark rays 
may be proved by allowing the light to pass first through a 
solution of iodine in bisulphide of carbon which permits 
the dark waves to easily pass while it cuts down or stops 
the light waves. When these dark waves are brought to 
a focus in w'ater it is made to boil quickly under their in- 
fluence. 

On the other hand if sunlight is first passed through a 
solution of alum in water, which stops the dark waves but 
allows the light waves to pass, then when they are focused 
upon water but little heating effect is noted. 

29. How Water is Evaporated. — It is the fact that water 
does not allow the long dark waves from the sun to pass 
readily through it which causes it to evaporate so rapidly 
from ocean, lakes and streams, and from the soil and the 
leaves of vegetation. When these Avaves fall upon water 
they set its molecules in such rapid vibration that the sur- 
face tension, or force of cohesion, is overcome and many of 
the water molecules are thrown out into the air in the form 
of invisible vapor. Were the w^ater not so opaque to the 
dark Avaves, neither snow nor ice would be as rapidly 
melted in the spring nor would there be so much evapora- 
tion from the ocean as we now have, hence rains would be 
less frequent and the land less productive. 

30. How Chemical Changes Are Produced by Ether 
Waves. — When the light waves and especially the shorter 
dark waves fall upon many substances they appear to set 



25 

iij) vibrations within the molecules themselves, vhich in 
time may become so intense as to overcome tlu^ force l)y 
which the components are bound together and the molecule 
is thrown into parts, setting- them free so tliat when their 
motion slows down thev may join in new combinations. 
It is much as if some giant power w-ere to seize upon a steel 
chain, throwing it into such intense vibrations that its sev- 
eral links are broken. 

31. Nature of Heat and Cold. — ^Vlien a body becomes 
warm the rate of vibration of the molecules which compose 
it is increased and the path through which they move 
becomes longer. If the body becomes cold the rate of 
movement of the molecules becomes less rapid and the dis- 
tance through which they move less. The higher the rate 
of molecular motion within a given body the warmer that 
body is and vice versa. If the molecular motion of a body 
could be completely brought to rest its temperature would 
be absolute zero. Under this condition it is supposed that 
any body would have its smallest volume ; and all liquids 
and gases would become solid. 

32. Temperature. — When tlie temperature of a body is 
given it is intended to state the degree of molecular vibra- 
tion within it. The temperature at which a Fahrenheit 
thermometer marks zero is not that of no molecular motion 
but simply 32 degrees of that scale slower than the rate at 
which pure water becomes a solid ; while zero indicated by 
a Centigrade thermometer is the rate of molecular motion 
which permits water to become solid and is a temperature 
273 degTces above what is assumed to be absolute zero or 
the condition of absolute rest. 

33. How Temperature is Measured. — It is a general law 
that those substances which may exist as solids, as liquids 
or as gases', as is the ease with water, which we know as ice, 
water and steam, or invisible vapor, change from the solid 
to the liquid forui and from the liquid to the gaseous form 
when the rate of molecular motion has reached a certain 



26 

degree, and this being true the freezing and boiling points 
of various substances may be taken as standards of tem- 
perature. 

Water being a common substance which changes its state 
at convenient and common rates of molecular motion has 
been selected to fix two degrees of temperature called the 
freezing and boiling points of water. When a thermom- 
eter scale is to be graduated its bulb is placed under the in- 
fluence of melting or freezing water, and the place at which 
the moving jDoint comes to rest marked ; then it is placed 
under the conditions of boiling water and the new point 
also marked. The space between these two points on the 
scale is then divided into 80, 100 or 180 divisions, accord- 
ing to the system which it is designed to follow. Since this 
range in molecular vibration is divided into 180 degrees on 
the Fahrenheit scale its degrees are the shortest, while 
those of the Reaumer scale are the longest because the same 
range is divided into but 80 divisions. 

The Centigrade and the Fahrenheit scales are the two 
commonly used in this countr}', the degree of the former 
being equal to y of the latter. 

34. Accuracy of Thermometers. — The bulbs of most ther- 
mometers shrink after they are blown and if they have not 
been permitted to stand for a number of years to season 
before fixing the zero and boiling points of the scale, these 
points will change and the thermometer will give incorrect 
readings in time and the cheaper grades of thermometers 
are liable to be subject to this error. 

The accuracy of the freezing point may be approxi- 
mately tested by surrounding the bulb with snow or 
crushed ice out of which the melted water may drain, al- 
lowing the thermometer to remain until the temperature 
becomes stationary. 

The accuracy of the boiling point may also be approxi- 
mately determined l)y holding the bulb in rapidly boiling 
soft water. 



27 

A thcnnoineter may be eorrect at the freezing and boil- 
ing- points and inaecnrato at most intervening degrees, 
growing out of the nneqnal diameter of the tube in differ- 
ent portions and the fact that all degree marks may be 
made of the same length. Errors of this sort can be de- 
tected only by comparing the thermometer with a standard. 

35. Units of Work and Energy. — It has been found neces- 
sary in dealing with the numerical relations of work and 
energy to adopt standards of measurement just as has been 
done for lengths, volumes, surfaces and mass, and various 
units are in use. 

36. Foot-pound and Foot-ton. — A common unit of work 
is the foot-pound, which is a mass or weight of one pound 
lifted vertically against or in opposition to the force of 
gi-avity. 

If a body is moved one foot in any other direction than 
against the force of gravity and the intensity of the pull 
or push necessary to do this is equal to that required to lift 
one pound, then in this case the work done is one foot- 
pound. If 2,000' pounds is lifted one foot high then 2,000 
foot-pounds of work have been done, and this is sometimes 
designated a foot-ton. The same intensity of pull in any 
other direction may be expressed in the same terms. 

Time is not a factor taken into account in simply ex- 
pressing the amount of work done for the reason that a 
very small force when permitted to act for a very long 
time may raise tbe same weight through one foot, which 
would require a very intense force if permitted to act but 
a very short time. 

37. Horse-power.^ — When the rate at which work is done 
and the intensity of the force required to do the work at 
the stated rate are to be expressed quantitively, then a 
unit involving time must be chosen and the horse-poiver 
is one of these. The horse-}X)wer used liy English and 
American engineers is the amount of energy which can 
do 550 foot-pounds of work per second or 33,000 foot- 



pounds per minute, equal to 16.5 foot-tons in the same 
time. To raise grain in an elevator to a liiglit of 20 feet 
at the rate of 16.5 tons per minute would require 20 horse- 
power. 

If a horse is walking 2.5 miles per hour and exeTting a 
steady pull on his traces of 100 pounds then the effective 
energy he is developing is 

100X5,280X2.5 

60 X 60 X 550 ~ '' 

and this for a well fed horse weighing 1,000 pounds, work- 
ing 10 hours per day at the rate of 2.5 miles per hour, is 
called a fair day's work. If a 1,500-pound horse could 
do work in proportion to his weight then his ability to de- 
velop energy would be equal to the standard English horse- 
power of 550 foot-pounds per second. Gen. Morin, how- 
ever, has placed the ability of the average horse to do work 
at the rate of 435.8 foot-pounds per second. 

38. Heat Unit. — In the steam engine the energy of heat 
is converted into work, and since heat is a form of molecu- 
lar motion its quantity must have a fixed relation to the 
temperature of a given amount of material. The English 
and American heat unit is the amount of heat energy which 
is required to raise the temperature of one pound of pure 
water from 32° F. to 33° F., and since on(^ form of energy 
may be converted into another the value of a heat unit may 
be expressed in foot-pounds. The English scientist, Joul, 
was tlie first to measure the number of foot-pounds of work 
which one heat unit could do and found it to be 772, which 
when corrected for the mercurial thermometer became at 
15° C. 775 foot-pounds. Rowland obtained the value 778.3 
foot-pounds. This means that the source of heat which is 
able to raise the temperature of one pound of water one 
degree every second would also be able to raise 778.3 
pounds one foot higli in the sauie time. 

39. Determination of the Mechanical Equivalent of Heat. 

— In order to ascertain the value of the heat unit in foot- 



29 

jMiuiuls, Joul an'aii<i('(l a, vessel containinii; watci' in such 
a way that In' incaiis of nicely adjusted \vei<;lits he could 
cause them to drive a set of ])a(ldles in the water and by the 
mechanical agitation warm it. By knowing the number 
of pounds in his weights, the distance they were allowed 
to fall and the rise in temperature which was observed in 
a given weight of water, he found the relation to be that 
stated in (38). 

40. Specific Heat. — We have learned (32) that tempera- 
ture is a measure of the rate of molecular motion within a 
given body ; it is not, however, a measure of the amount of 
work which must be done upon that body to change its 
temperature through a given number of degrees ; neither is 
it a measure of the amount of work which may be secured 
from that body when its temperature falls a given amount. 

When the same number of heat units is imparted to like 
weights of diiferent substances their tem2>eratures are not 
raised through an equal nund>er of degrees. The same 
amount of heat, for example, which will raise the tempera- 
ture of one pound of water from S2° F. to 33° F. will 
raise a pound of sand from 32° F. to 37. 23^^' F. For some 
reason more work must be done on water than on the sand 
to secure the same change of temperature, but, true to the 
law of the conservation of energy, when the water again 
cools down it gives out as much more heat in doing so as 
was required to produce the rise in temperature. It is 
this fact which causes large bodies of water to make the 
winters of adjacent lands warmer and the summers cooler. 
Soils change in temperature more rapidly than would be 
the case were their specific heats higher, and for this rea- 
son in part a wet soil is cooler than the same soil when 
dryer. 

41. Latent Heat— When ice ..t 32° F. has heat applied 
to it its temjierature does not rise so long as there is still 
ice to melt, the whole of the energy given to it being con- 
sumed in changing the solid ice into liquid water, that is, 



30 

in doing tlie Avork of melting. The amount of heat re- 
quired to melt one pound of ice is 142 units when ex- 
l^ressed in round numbers ; or if the work done is expressed 
in foot-pounds it will be 

142 X 778.3 = 110,518.6 foot-pounds 

and the time required for one horse power to do the work 
would 1)0 

110,518.6 oo- • , 
33,000 -3.30 minutes. 

When crushed ice and salt are mixed in the ice-cream 
freezer the changing of the two solids to a liquid requires 
so much energy, and it is used so rapidly, that the cream is 
quickly frozen, its molecular motion being used in doing 
the work. 

When water has been brought to the boiling tempera- 
ture it ceases to become warmer so long as boiling contin- 
ues, all of the heat energy entering from the fire being re- 
quired to do the work of changing liquid water into steam. 
The amount of heat required to change one pound of water 
at 212° F. into steam at the same temperature is 966. & 
heat units. When expressed in foot-pounds it becomes 

778.3X966.6 = 752,305 

and the time required for one horse-power to do this work 
is 



752,305 „. . , 
g^P^^^ = 22.8 minutes. 



When a pound of water at 32° F. becomes ice at 32° F. 
there reappears as heat tlie 142 heat units which were re- 
quired to melt it, and so too when one pound of steam con- 
denses into water there reappears 966.6 heat units. Be- 
fore the nature of these changes were as well understood as- 



31 

they ii»»\v arc, it Mas siqiposcd that tlic licat bceamo hidden 
01" latent l)iit that it was heat stilL 

42. Measuring the Energy Required to Melt Ice. — This 
may he deteriniued appruxiinately by taking equal weights 
of water at 212° E. and of ice at 32° F., putting the two 
together and noting the temperature at the moment the ice 
is all melted. When this has been done it will be found 
that the combined water has a temjx^rature of about 51° F. 

If, however, equal weights of water at 32° and 212° are 
mixed there will be found a temperature of 

212 + 32 

^ = 122 

one volume of water having lost as much as the other 
gained. 

In the first case, however, the water lost 

212 — 51 = 161 
while the ice gained only 

51 — 32 = 19. 
There was therefore in this ease an apparent loss of 

161 — 19 = 142° 

If a pound of water and of ice had been taken for these ex- 
periments it is plain from (38) that the 142 would also 
represent 142 heat units. 

43. Measuring the Energy Required to Evaporate Water. 

■ — If a pound of steam at 212 ' F. be condensed within 5.37 
jwunds of water at 32° F. there will result 6.37 pounds of 
water having a temperature very close to 212° F. The 
one pound of steam has therefore raised the temperature of 
5.37 pounds of water through 



32 

212° — 32" = 180° 

without having its temperature materially lowered. The 
molecular energy, therefore, which the one pound of steam 
contained was 

180 X 5.37 = 966.6 units. 

This large amount of energy in steam explains how it is 
able to do so much work when acting upon the engine pis- 
ton and Avhj a burn from steam may be so much more se- 
vere than that from boiling water. . 



49 



PHYSICS OF THE SOIL. 



CHAPTER I. 

NATURE, ORIGIN AND WASTE OF SOIL. 

64. Nature of the Soil. — The great bulk of most soils is 
made u]) of small fragments of rock of various kinds, but 
nearly always there is associated with these varying 
amounts of organic matter derived from the breaking down 
of plant and animal tissue. 

On the surface of the soil gTains, too, there is always ad- 
hering more or less of substances which have been dis- 
solved in the soil-water but which have been deposited again 
when the water Avas evajDorated. 

In most soils, but chiefly in the clayey types, there oc- 
curs some aluminium silicate having water combined with 
it, which is regarded as giving to them their sticky, plastic 
quality when wet. The amount of this material in a good 
soil is always small, seldom reaching more than 1.5 per 
cent., but the particles are so extremely minute that very 
little by w^eight has a marked effect upon its character. 

65. Soils and Sub-soils. — In climates where the rainfall is 
sufficient for large crops it is common to speak of the sur- 
face few inches of rock fragments as the soil while that 
below is known as the sub-soil. The fundamental reason 
for making this distinction is found in the fact that the 
latter is less productive than the surface soil. So general 
is this difference in fertility that tlie term ''dead-furroV 
has been universally applied to the finishing of a land 
in plowing where the two furrows are thrown in opposite 



50 

directions, leaving the sub-soil exposed, and where crops 
are always smaller. On the other hand, where two fur- 
rows are thrown together to form the "back-furrow" and 
the depth of soil increased crops are notably more vigorous. 

We do not yet know just why a sub-soil when exposed 
to the surface is less productive than the true soil, but the 
difference seems in some way to be associated with the 
larger per cent, of the extremely minute particles which 
sub-soils contain. 

In arid regions where the rainfall is not sufficient for 
crop production it seldom occurs that the deeper soil is 
markedly different in productiveness from that at the sur- 
face. Soil taken from the bottom of cellars and even from 
depths as great as 30 feet is found quite as productive 
w4ien placed upon the surface as the top soil. So gener- 
ally true is this that when it is desirable to level fields for 
purposes of irrigation in arid climates the soil from the 
higher places may be scraped to the lower levels without 
fear of lessening the productiveness of the fields. 

66. Uses of Soil. — In the agricultural sense the most im- 
portant use of soil is to act as a storehouse of moisture for 
the use of plants ; and the productiveness of any soil is in 
a very large degree determined by the amount it can hold, 
by the manner in which it is held and by the readiness and 
completeness witli which the plant growing in it is able to 
withdraw that water for its use as needed. 

In the second place, the soil is a storehouse from which 
plants derive the ash ingredients of their food, the lime, 
the potash, phosphoric acid and other materials of this class, 
all of which are derived from the slow decay and solution 
of the soil grains. 

Besides these the soil is a laboratory in which a great 
variety of microscopic forms of life are at work during 
the warm portions of the year, breaking down the dead 
organic matter of the soil, converting it into nitric acid 
and other forms available to higher plants, and the student 
must never forget that the magnitude of the crop taken 



51 

from the field is always in proportion to the size of the 
crop developed by the micro-organisms in the soil. 

Then again, the soil is a medium in which plants may 
jilace their roots in such a numiier as to enable them to 
stand erect in the open sunshine and moving air currents 
above. 

Finally, the soil is a means whereby the sunshine is 
changed into forms of energy available to the needs of soil 
organisms and the roots of plants and without which this 
life could not exist ; for all of its movements must originate 
l)rinuirily from the sunshine altered in the soil or in the tis- 
sues of the plant above the soil. 

67. Formation of Soil. — There are many agencies at work 
in the formation of soils and the processes of soil growth 
are in continuous operation day and night, winter and sum- 
mer. Since all soil material originates from the breaking 
down of the various rock structures which make up the 
earth's surface all of the agencies which are operative in 
rock destruction may also contribute to soil formation. 

68. Influence of Rock Texture on Soil Formation. — Xearly 
all kinds of rock are made up of fragments or crystals of 
various sizes and shapes and these are held together by in- 
terlocking, by some cementing material, or else by direct 
cohesion when extreme pressure has brought the grains 
close enough together to make this possible. It is seldom 
true, however, that the structure is so close or the cement- 
ing so complete as to make the rock impervious to water 
and the closest granite or the finest marble may absorb 
as much as .1 to .4 of a pound of water to 100 pounds of 
rock. If this water is chauging it will dissolve away the 
cementing materials and the faces of the crystals them- 
selves, making the rock still more open and the gTains may 
even fall apart as is frequently observed in tliose cases 
known as "rotten stones." 

The water may freeze in the stone and by its expansion 
cause it to crumble. Or again, when the sun shines on 



52 



rocks made up of minerals of different kinds the crystalr* 
do not all expand at the same rate and this unequal expan- 
sion and contraction tends to loosen crystals and fragments^ 
breaking the rock down, and thus form soil. 




Fig. 8. — Section of limestone hill showing rock changing to soil. 
(After Cliamberlin.) 



69. Formation of Soil From Limestone. — If one will visit 
any limestone qurarry where the soil and rock are exposed 
in section as represented in Figs. 8 and 9 it will be 
clearly seen how the rock is slowly converted into soil. In 
such cases as these, the water containing carbonic or other 
acids dissolves away the lime and magnesia, leaving the 
more insoluble portions of the lime rock to form the soil 
mantle which is left. These more insoluble portions are 
usually clay and very fine sand so that soils formed in this 
way are oftenest clayey soils, sometimes containing even 
less lime than other soils not derived from limestone. 




Fig. 9.— Section of flat limestone surface showing rock changing to soil. 
(After Cliamberlin.) 



The mantle of soil seen above gravel beds in railroad 
cuts and where hills have been graded down on wagon roads 
has usually most of it originated from the decompositioa 
of the gravel in place in the same manner as a soil from 
the limestone itself. So, too, in countries where granite 
and other crystalline rocks lie beneath the soil, these have 



53 




])Ovu Id'oki'ii (IdWii ;iii«l 
the over-lyiiii;' soil de- 
rived from tlu'iiL 

70. Influence of Rock 
Fissures.— All cxMiniii;!- 
tioii of aliuiist aiiv (piar- 
ry where eonsidcrahle 
surfaces are i xpost-d re- 
veals the ])reseiK'e of 
systems of fissures which 
divide the stone hiyers 
into lilot'ks of various 
sizes and at the same 
time provide easy nvi:- 
nues for the entranee of 
surface Avaters. Tht'se 
features are shown 

clearly in Fili'S. 10, 11, Fu; H- Fort Danger, Wis., .^liowiair rock lis- 
10 rm/l 1 Q .T,wl i,,+^ sures wliich lead to ruck desjiuctiou. (After 
1^ ana lo, ana into cuamberlin.) 

them the roots of trees 

sometimes make their 
way where by expansion, 
(hie to growth, such strong- 
pressures are devoloped 
as sometimes to throw 
down large blocks of 
stone. Then again, in 
cold climates these tis- 
siires may become tilled 
with water which, when 
I freezing, overturns and 
throws down manv frag- 
ments, thus hastening 
their ])assage into soil. 

71. Soil Removal. — Tt 
follows from what has 
been said that the same 
processes which result in 

1" IG. 4— lic(f Hlull', Wis , ^howiiid rock fis.^iirps ^ . , ,. . ■, 

wliich Icui to rock destruction. (After Soil formation lllUSt alSO 
Cliainberlin.) , •, , , •, i , 

contrihute to its destruc- 




54 



f^3 




tion in one place or re- 
moval to another. All 
are familiar with the 
creeping of soils from 
the broAvs of steep hill- 
sides toward their bas( 
and ont npon the mun 
level ]:)1 a ins which 
stretch away from them. 
These downward'move- 
ments are caused bv sca 
eral agencies: (1) Tli 
beating of falling raii 
drops and the carrying 
230wer of the streandet^ 
wdiich fV)rm as these 
gather together ; {2) the 
expansion and contrac 
tion of the soil due to 
the alternate wetting 

and drving, there being Fig. rz.— Giant's ('a.-flcncarCamp Douglas, 
n„ '• , , Wis., showing cliffs of rock crumbling into 

less resistance to expan- soil. (After Cliamberlin.; 

sion dowin\'ard than upward against gravity. These 
movements are analogous to those of the steel rails of 
the railroad which tend to creep down grade under the 
influence of changing temperature, which causes them to 
first lengthen and push down hill and then shorten and 
again draAV downward because of less resistance in that 
direction. (3) Then, again, every disturbance of the 
soil produced by animals burrowing or walking up or doA\ni 
the hillside, tends usually to work the soil from higher to 
lower levels. Even the action of the wind is on the whole 
doAmward. 





72. Soils Produced by Running Water. — Eivers and 

streams are contiiinally at work at this double process of 
soil building and soil removal. When one watches the bed 
of a stream as the water rijiples over the uneven surface 



55 



it is oas^y to note how I'apidly soil and sand grains are be- 
ing rolled and tiiiid)lcd along the bottom. If it is desired 
to nieasnre this rate of movement a shallow pan or box 
may be sunk in the 
bed of the stream, 
leaving its rim Hnsh 
M'ith the surface ovei- 
Avbieh the water i-olls. 
After a sufficient in- 
terval remove the box 
and dry and weigh 
the material collected. 
At each bend in a 
stream soil is l)eing 
taken from the con- 
cave side and carried 
onward toward the 
sea, while on the o])- 
posite side new soil is 
being formed from 
that draggXM 1 ah )ng 
the bottom. In this 
manner streams 
change their courses 

1 1 J? • 1 Fig I'-i — Pillar Rock, Wi-;.. sliowinff rocliy cliff 

ana wander irom SUle in tUe last stages of decay. (After Cbamber- 

to side across the val- ^'"'^ 

ley, each time making a new soil 03i tlie side from which 
they are retreating and carrying away an older soil from 
the encroaching side. It is in this way that broad and 
flat river valleys are formed, with their terraces, sucli as 
are shown in P"'ig. 14. It is in this way, too, that the '^'ox- 
hows" (if the ^Mississippi below Vicksburg were formed, 
some of which are re])resented in Fig. 15. 

These abandoned river channels are at tirst long and 
narrow lakes hut ultimately, with the rejx'atcnl overflows 
of the stream, they became filled. Sometimes they remain 
for long intei'vals de])ressions in which swam]) or humus 
soils develoj). 




56 




O ( 




Fig. 15.— ShowiLg the sliiftin^^ of river chanaels, the formation of "ox-bows' 
and alluvial soils. 



73. Glacial Soils. — In those portions of the world where 
the temjieratni'c is so low that most of the moisture falls 
as snow and where these snows do not all melt dnrine; the 
warm season there come to be sneli vast accnuiiihitions that 
the areat weii>lit eompresses the snow into ice. So ex- 
tensive and massive are these snow and ice fields in Green- 



58 




59 




60 



land and in parts of Alaska today that tliev move over the 
face of the eonntry miicli as a broad river would move,, 
except at a much slower rale. The same type of phenom- 
ena occur, too, in the elevated mountain districts of Europe 
and in the Sierras of this country, the ice streams con- 
verging and flowing into the lower valleys in the form of 
glaciers. As these ice streams move over the uneven sur- 
face of their valleys and crowd against their sides, the 
rocks, gravel and sand taken up by the moving ice act with 
great effectiveness to ahraid into soil the rigid rock surfaces 
over which thev move. 




^iiG. 18.— Shovvitiiarrock surface over which glaciers have passed, scratching and 

polisliing it. 

In a recent geological epoch the whole of the Xorth 
American continent north of the Ohio and Missouri rivers 
and much of northern Europ,e and Siberia were under enor- 
mous moving ice sheets which resulted in the formation 
of the extensive glacial soils of these countries ; consisting 
largely of a rock flour ground to varying degrees of fine- 
ness, and naturally very fertile where the materials have 
not been sorted by the waters from the melting ice in such 
a way as to form siliceous sandy ]dains. Eigs. 16, IT, 18 
and 19 are views illustrating different jdiases of soil forma- 
tion bv j>lacial action. 



61 




Fig. 19.— Relief Map of Wisconsin, showing the diti'erence in topography of a 
glaciated and non-glaciated surface. 



74. Formation of Humus Soils. — There is a class of soils 
having their origin in vari<;ns types of swamps or marshes 
^vllicll contain an nnnsnal anionnt of organic matter in va- 
rions stages of decomposition and Avhicli have by some 
■writers been given the name of hnmns or swamp soils, the 
former name referring to the large amonnt of hnmns these 
soils contain and the latter to the physical conditions iTnder 
which they have been formed. 

In many places in the higher latitndcs and at consider- 
able elevations nearer the eqnator where the snrface is too 
flat for ready drainage, and where the winter snows re- 
main so long npon the gronnd that the snmmer is too short 



62 



to permit the soil to l^eeome dry eiiono'li to allow the air 
to penetrate deeply and freely, the organic matter accn- 
nmlates and soils are formed containing a large proportion 
of hnmus ; even beds of peat may develop. 

Under other conditions, where rivers ap- 
proach their outlet across a very flat country 
t and are no longer able to scour their clian- 
.5 nels and keep them clean, the moving sedi- 
I ment finally raises the banks and the bed un- 
rt til the water is flowing above the surround- 
^ ing country. Under these conditions with a 
a continual seepage and frequent overflows 
=« swamps are developed in wdiich marsh vege- 
^ tation grows luxuriantly and, falling under 
§ conditions where free oxidation cannot oc- 
J cur, the renuiins only partially deca,j, giving 
^ rise to beds of peat and rich humus soils. 
f In other cases, where a river often shifts 

1 its course and especially where the cut-offs 
o or ox-bows illustrated in Fig. 15 are formed, 
.2 these places, with the poor drainage which 
g they must have and with the occasional over- 
o flows to keep the cut-offs filled Avith water, 

are maintained wet long and continuously 

2 enough to allow humus soils to form. 

1 With the final withdrawal of the great ice 
^ sheet from the glaciated parts of America 
•| and Europe there were left large numbers of 
J shallow lakes whose flat margins were wet 

j enough to support marsh vegetation and 
° very often this vegetation came to form a 

2 floating fringe steadily encroaching upon 
the lake in the manner represented in Fig. 
20. As the vegetation continued to grow 

and die the fringe became heavier and sank more deeply in 
the water until finally the whole lake was overgrown and 
until the organic matter, together with the sediments 
brought down by the rains and the winds and washed in 



6( 



from tlio snrvdiiiidiini- liiiilu'r land, became so heavy and so 
thick as to rest upon the bottom of the lake, converting it 
into a marsh of peat or hnnins soik 

On the margins of larger lakes and 
especially along the seashore, sand bars 
or reefs are thrown n]) behind which 
bodies of water are shut off and in 5 
these organic matter may accumulate ii 
in the same manner as that iust de- ' 

c — 

scribed, giving rise to the same type of 5 
soils. =■ 

In still other cases, on the margins I 
of the sea bottom, there flourishes a pe- | 
culiar type of vegetation known as eel ^ 
ffrass, which lives alwavs beneath the C 
water at low tide in a position repre- 



sented in Fig. 21. 



These a'l'asses offer ?. 



a natural obstruction to the incoming ^ 



and 



outgoing tidal waters, causing &■ 
them to throw down their sediments 3 
and thus build up the sea floor with :;; 
silt containing large amounts of or- ■=■ 
ganic matter under conditions unfav- 2 
orable to rapid decay. As the sea floor ^ 
rises in this way above low tide level % 
the eel grass dies and another type of 5- 
swamp vegetation takes its place, as % 
between a and b in the figure, and here g, 
again the formation of humus soil is « 
continued under somewhat dift'erent ^ 
conditions. 

75. Wind-Formed Soils. — The wind 
moving continuously o\'er the face of 
the land is now and long has been a potent factor in soil 
removal and soil Iniilding. Iiid(H-d, it is probable that 
nowhere can soils be found which do not contain many 
wind-borne ])articles. Every raindrop which falls and 
every suowflakc, however white, brings to the field upon 



j^ 



64 

Avhicli it falls one or more particles of soil Avliicli has been 
drifting in tlie higher air from unknown distances. 

The drifting of dnst from roads during dry times and 
from fields in the spring are strong reminders of the po- 
tency of wind action at times, but it is the less evident but 
continuous action that counts most in the long run and, 
were it not for the steady wearing away and rearrangement 
of the soil surface, wjnd-formed soils would be much more 
evident and general than they are. 

On the leeward margins of arid regions and on sandy 
coasts the building and eroding power of the wind becomes 
most evident, and the most extensive deposits which have 
been assigned to this cause are the loess beds of China 
which have great horizontal extent and in some places 
depths reaching even 1,200 and 2,000 feet. These depos- 
its have been described by Richthofen as having been 
formed from dust accumulations drifted by the prevailing 
winds from the high desert plateaus of Central Asia. 

In Enrojje, and in this country in the Mississippi vaL 
ley, there are deposits of a similar character. They are 
distributed along the border of a former ice sheet of the 
glacial period and from thence they spread down the main 
streams, along the Mississippi from Minnesota to near the 
Gulf, along the Missouri from Dakota to its mouth, and 
along both the Illinois and the Wabash. These deposits 
are thickest, most typical and coarsest along the bluffs 
nearest to the streams and they thin out and become finer 
as the distance back increases. It is thought that the fine 
silts borne along by the waters of the glacial streams in 
times of high water were spread out over broad flats and 
as the waters withdrew they were left to dry in the sun 
and then picked up by the winds and drifted away. The 
loess soils are almost always extremely fertile and very en- 
during. 

76. The Work of Animals as Soil Producers. — Tlu re are 
many animals Avhicli have contributed largely to the forma- 
tion of soil through a grinding of pebbles and the coarser 
sand and soil grains into finer materials. 



65 



Darwiiu tlirouiili a louii; and cai-cful studv, reached the 
conehision that in inaiiy [)ai'ts of Kiitiland eartlnvorins pass 
more than 10 tmis of dry earth per acre through their 
hodies annually and that the grains of sand and hits of flint 
in these earths are i)artly worn to fine silt by the muscu- 
lar action of the gizzards of these animals. Their method 
of action in moving through the soil is this : They eat a 
narrow hole, swallowing the earth, when the point of the 
head is held fast in the excavation while an enlarged por- 
tion of the tt'sophagus or swallow is drawn forward, forc- 
ing the cheeks outward in all directions, thus crowding the 
soil aside and making the opening wider, when more dirt 
is eaten and the operation repeated, allowing the animal 
to advance through the soil. 

Domestic fowls and all seed-eating hirds, in picking up 
pebbles for service in grinding their food, do the same sort 
of work as the earth- 
worms in producing 
fine soil, as every 
housewife can testify 
from the worn condi- 
tion of bits of glass 
and pottery taken from 
the gizzard of the 
chicken. 

. 77. Soil Convection. — 
There is another very 
important line of work 
done by earthworms, 
ants and all burrowing 
animals, in bringing 
the sub-soil to the sur- 
face and carrying the 
surface soil into the 
ground, thus maintain- 
ing a sort of soil-con- ^—'^^^—~ .,= ,=-5-— ^- 

i-or-+i<^n ■ii'lnV.li in ^.+'.FiG. 23 — A tower-like casting ojected by a spe- 

Aecrion AMUCII, in (l cies of earthworm, from the Botanic Garden, 

feet amounts to the Calcutta. India. Natural size from photo. 

' ' (After Darwin.) 







66 





V ^- i". ». . 








' *i- T" -' 




^% •% 


K' 


t:-^^ ^ 







'. .",> 






#^-' 



*•!', 

\**^ 



.■</*' 



■?■/■ 



: ^5 

•IS 



7 \ 



#'•: 



-r 



Fig. 23. —Showing the work of the common earth worm during a single night after 

a heavy rain. 



67 



same thiiiii,' as ])lowiii,ii,' cxcc'i)! that its influence extends 
iinu'li deeper. 

Both earthworms and ants often hnrrow in the ground 
to a depth of four feet, and in some cases more than nine, 
bringing- the material to the surface and forming passage- 
ways down which the rains maj wash the finer surface 
soiL Fig. '■2-2 shows a single pile of earth cast np by an 
earthworm in the Botanic Gardens of Calcutta, and Eig. 23 
shows the work of onr common earthworm during a single 
niiilit in hriniiini"' ui) soil after a rain. 

#ui'i\V'!iv,( «^'Vv^»v/i>^!iu' '^'AV'W^A^Vfi * /"\'i^'/'^^' ' 





o 



Fig. 2t.— Section of vegetable mould in a field drained and reclaimed 15 years 
before: ^iioxMtiK turf, vegetable moiild'. without ^t()ue•-, mould with frag- 
ments of buiut marl, coal cinders and <iuartz pebble^- buried under the 
influence of earthworms. One-third natural size. (After Darwin.) 

This fretjiieiit hvinging of earth to the surface tends 
to burv objects and gradnallv to lower them into the ground, 
and Fig. 2-^ rei)resents the results of one of Darwin's 
studies, showing the amount of soil which has accumu- 



68 

lated above bits of burnt marl, cinders and pebbles dur- 
ing 15 years, largely tlirongli this action of eartlnvorms 
and ants in bringing to the surface portions of the sub- 
soil. It will be seen that the amonnt accnniulated is more 
than three inches, or at the rate of an inch in 5 vears. 



GO 



CTTArTER IT. 

CHEMICAL AND MINERAL NATURE OF SOILS. 

78. Unsatisfactory State of Present Knowledge. — It is 

now pretty itcncrally coneeded that the capacity of a 
soil to feed crojjs of a given kind cannot be foretold with 
much certainty from the results of chemical analyses as it 
has been tlie custom to make and present them. It has 
been found, for example, in the arid west, that soils nota- 
bly delieient in huniic nitrogen and which for this reason 
should be comparatively unproductive, have, nevertheless, 
been found capable of giving large yields when irrigated. 
Then again, in moist climates there are types of soil ex- 
ceptionally rich in both humic and nitric nitrogen which 
are comparatively unproductive until they are given 
dressings of coarse farmyard manure. The analyst would 
j)lace them among the richest of soils and yet they are 
among the poorest until given farmyard numure; and, 
what appears stranger still, straw and coarse litter may 
be much more beneficial to them than liquids from the sta- 
ble cistern. 

79. Essential Constituents of a Fertile Soil. — While it is 
true that our chemical knowledge of soils is very unsatis- 
factory, it has nevertheless been thoroughly established that 
a fertile soil must contain certain substances in order to 
permit any crop to come to maturity upon it and these are 
potassium, calcium, magnesium, phosphorus, sulphur, iron, 
nitrogen and probably chlorine. Let any one of these ele- 
ments be absent from a soil, or its moisture, and crops fail 
to develop upon it. It has not, however, been established yet 
in what form of condnnation tliese elements must or may 
exist nor in what jiroportions to give the best results. It 
is known tliat they do not exist in the soil in the elementary 
form and that thev are coin])ined in a o-roat varictv of wavs. 



70 

Furthermore, from these combinations, under favorable 
conditions, plants are able to supply their needs. 

80. Functions of the Essential Plant Foods. — From the 

standpoint of plant physiology it is again unfortunate that 
little has yet been positively demonstrated regarding the 
l^art played by each of the essential elements of plant food 
taken through the soil and soil moisture. It is known that 
nitrogen is an essential constituent of the protein com- 
pounds of living tissues, and that to most of the cultivated 
crops it becomes available in the form of nitric acid or of 
a nitrate of lime, magnesia, potash or some other base. Po- 
tassium does not appear as an essential ingredient of plant 
tissues or of its storage products like starch or gluten, but 
N^obbe, Schroeder and Erdmann have shoAvn that when 
JajDanese buckwheat, placed in nutritive solutions en- 
tirely free from potash salts, after a few weeks' growth 
came to a standstill and that all organs of the plant came 
to be nearly or quite free from starch ; but when a potas- 
sium salt was added to the solution starch began to develop 
and growth became normal. 

In regard to phosphorus the clearest indications go to 
suggest that it is usually taken into the plant in the form 
of phosphates and, because its compounds are often asso- 
ciated with the soluble albuminoids, that it assists in some 
way in the transfer of these from place to place in the plant. 

Some compound of iron must exist in soil solutions and 
must enter the plant before the normal development of the 
green coloring matter, chlorophyll, can take place ; so ex-- 
tremely small quantities, however, are needed that no soil 
is ever lacking in sufficient available forms. 

Sulphur is apparently largely if not wholly taken into 
the plant in the form of sulphates, and these are thought to^ 
be decomposed by the oxalic acid, setting the sulphuric acid 
free, wdiich is then broken down and the sulphur appro- 
priated to enter as an essential constituent of the albimiin- 
oid compounds. 

But little is known of the j)art played in plant life by 



71 

the salts of iiiagnosia except that they iiinst he present in 
the seed. 

The action of lime is held to be medicinal, its function, 
being to neutralize the poisonous oxalic acid liberated as 
an intermediate product in the oxidation of carbohydrates. 

Large amounts of silica and almnina and smaller 
amounts of many other substances are found in the ash of 
plants but their presence there is regarded as accidental, 
growing out of the simple fact that they chanced to be dis- 
solved in the soil-water and passed into the tissues with it 
during growth. 

81. Chemical Composition of Soils. — From what has been 
said regarding the origin of soils and the numner in which 
their particles have been moved from place to place, it is 
evident that there must necessarily be a strong similarity 
among them, of both chemical and mineral composition^ 
wherever found. It has been customary in analyzing soils 
to digest a certain weight of dry soil for a stated time in a 
certain strength of hot hydrochloric acid and to examine 
the solution for the compounds it might contain, calling the 
part not dissolved the insohihJe residue. The tables on 
pages 74-75 show the results of some of these analyses, 
taken from the papers of Hilgard in the Tenth Census of 
the United States. 

82. Chemical Difference Between Clayey and Sandy Soils. 

— Studying tli(^ tabic of clayey and sandy soils it will be 
noted that out of every 100 pounds of the clayey soil there 
were, as an average, 31.791 pounds which dissolved in hot 
hydrochloric acid, while only G.79 pounds were soluble in 
like weight of the sandy soil. In other words, a quarter 
of the Aveight of the clayey soils more than of the sandy soils 
is soluble in a unit of time in hot hydrochloric acid. There 
is about 2.5 times as much potash and organic matter, 
nearly twice as much phosphoric acid, 7 times as much 
lime, 9 times as much magnesia and 1.1 times as much 
sulphuric acid in the clayey as in the sandy soil, which 
may be dissolved out in equal times by the solvent used. 
These ratios, however, are sometimes a long ways from 



72 

true when single cases are coni])are(l, and this is shown in 
a striking manner in the single case of clay soil given below 
the lino of averages in the table of sandy and clayey soils. 
This is described by Hilgard as a fair upland soil yielding 
700 to 800 pounds of cotton per acre, gray in color, not 
heavy, 6 to 8 inches deep, and underlaid by a subsoil quite 
heavy in tillage aud dark orange in color ; and yet its in- 
soluble residue is about 91 per cent, and there are two of 
the sandy soils where the per cents, are 90 and 92 respec- 
tively, showing ihat the two are more ncnirly alike chemi- 
cally than they are physically. 

83. Observed Chemical Differences, Partly Due to Differ- 
ences in Amount of Soil Surface. — It is a ('oiniuon experience 
that the more linely a substance is subdivided the more 
rapidly will it dissolve. Fine salt and powdered sugar, 
for example, dissolve much more rapidly in water than the 
coarser grained varieties do. In the clay soils the particles 
have a much snudler diameter than they do in the sandy 
soils and hence the nund)er of grains in a given weight of 
soil will be much larger, but the nund)er of grains cannot 
be increased without also increasing the surface upon 
which the solvent may act, and hence with the same 
■strength and amount of acid, for equal weights of the coarse 
and fine grained soil, having exactly the same chemical 
•composition, there should be dissolved in equal times a 
larger per cent, of the soil having the largest amount of sur- 
face. The sandy soils therefore are not likely to be as dif- 
ferent from the clayey ones as the table of analyses indi- 
cate. 

84. The Chemical Differences Between Soils and Their 
Subsoils. — In humid climates there is usually a nnirked dif- 
ference in the producing capacity of the soils and their sub- 
soils as was pointed out in (65), and a study of the table 
of s\d)soils, ])p. 74, 75, will show that there is a chemical 
difference also. It will be seen that tlie surface soils con- 
tain more lime, phosphoric acid and organic matter, less 
soluble silica, alumina and iron and about the same 
amounts of potash, nuignesia and sulphuric acid. 



73 

85. Comparison Between Clay Soils and Swamp Soils. — If 
a eoiiiparisoiL is made between tlie clayey soils, wLicli are 
generally productive naturally, and the Imnius soils it will 
be seen that the latter contain about twice as much potash, 
magnesia, sulphuric acid and organic matter, six times as 
much lime and a littU^ more phosphoric acid, and yet for 
some reason the humus soils, when well drained, may not 
naturally be as productive as the clay soils are and here is 
where the present methods of soil analysis fail to tell the 
whole truth. 

86. Comparison Between Clayey Soils and Loess Soils. — ■ 

The loess soils do not show a much larger pei'centage 
amount of the essential ingTedients of plant food than do 
the clayey ones. Indeed there is less of organic matter and 
only a little more of potash, phosphoric and sulphui'ic acids. 
The chief and great difference lies in the large amount of 
lime and magnesia Avhicli they contain, the first being more 
than 9, and the latter more than 8 times as large. If it is 
true that these soils are largely wind-formed it is to be ex- 
pected that these two substances would appear at the sur- 
face to be taken up by tlu^ winds more than any ()ther of the 
essential ingredients, first, because they are comparatively 
soluble and hence likely to be brought up by the ca})illary 
waters and left after evaporation where the wind has free 
access to them ; and second, because they are not so soluble 
as to be completely dissolved by the heavy rains and car- 
ried back into the ground again. 

87. Difference Between Arid and Humid Soils. — The soils 
which have accumuhited in the arid climates of the world 
are quite markedly different from those of the more humid 
portions, botli in ydiysical and chemical properties. The 
per cents, given in the talde of arid and humid soils are 
those of Hilgard and are averages of 4^0 analyses from hu- 
mid climates and 313 from arid. 

It will be seen that the arid soils contaiu more than 3 
times as much potash, neai-ly 13 times as much lime and G 



Chemical coniposiUon of soils. 

Essential ingredients in per cent, of dry soil. 















Phosphor- 


Sulphuric 


Water 


Potash. 


L] ME. 


Magnesia. 


ic Acid. 


Acid. 


AND 


KGANIC 
















Matter. 


Sand. 


Clay. 


Sand. 


Clay. 


Sand. 


Clay. 


Sand. 


Clay. 


Sand. 


Clay. 


Sand. 


Clay. 


.100 


.416 


.120 


.080 


.040 


.691 


.051 


.103 


.028 


.061 


2.055 


1.906 


.1.56 


.176 


.081 


•090 


.069 


.112 


.101 


.071 


.057 


.055 


2.642 


8.891 


.045 


.186 


.064 


.071 


.005 


.065 


.066 


.204 


.091 


.285 


2.422 


8.953 


.117 


.134 


.058 


.219 


.042 


.289 


.092 


.069 


.058 


.035 


1.807 


8.309 


.110 


.242 


.090 


.387 


.025 


.508 


.191 


.071 


.10.) 


.0.55 


3.477 


6.843 


.067 


.092 


.119 


.036 


.090 


.070 


.111 


.082 


.054 


.054 


2.881 


6.167 


.275 


.431 


.0.35 


.540 


.048 


.836 


.105 


.187 


.034 


.009 


3.682 


6.922 


.095 


1.104 


.076 


1.349 


.083 


1.665 


.039 


.304 


.045 


.024 


2.354 


7.369 


.209 


.150 


.141 


3.0.54 


.031 


.029 


.103 


.24i 


.046 


.089 


3.113 


4.962 


.034 


.255 


.045 


.340 


.013 


.296 
.456 


.014 


.079 


.035 


.079 


1.636 


4.962 


.121 


.319 


.085 


.617 


.048 


.087 


.141 


.055 


.075 


2.607 


6.528 




.137 




.173 




.203 




.088 






3.394 











SWAMP AND LOESS 


SOILS. 








Hu- 
mus. 


Loess 


Hu- 
mus. 


Loess 


Hu- 
mus 


Loess 


mus. I^-- 


Hu- 
mus. 


Loess. 


Hu- 
mus. 


Loess. 


.639 


.435 


3.786 


5.820 


.886 


3.692 


.150 .200 


.148 


.090 


13.943 


1.205 



SOILS COMPARED WITH THEIR SUB-SOILS. 

.SOILS. 



Sand. 


Clay. 


Sand 


Clay. 


Sand. 


Clay. 


Sand. 


Clay 


Sand. 


Clay. 


Sand. 


Clay. 


.157 


.214 


.115 


1.761 


.076 


.182 


.128 


.207 


052 


.090 


2.853 


6.014 



sub-soils. 



.143 


.344 


.096 
-H.019 


1.481 


.073 


.240 
-.058 


.124 .159 


.060 


.071 
+ .019 


1.943 

+ .910 


4.780 


+ .014 


-.130 


+ .280 


+ .003 


+ .004 +.018 


-.008 


+1.234 



ARID AND HUMID SOILS COMPARED. 



Hu- 
mid. 


Arid. 


Hu- 
mid. 


Arid. 


Hu- 
mid. 


Arid. 


Hu- 
mid. 


Arid. 


Hu- 
mid. 


Arid. 


Hu- 
mid. 


Arid. 


.216 


.729 


.108 


1.362 


.225 


1.411 


.113 


.117 


.052 


.041 


3.644 


4.94.5 



75 

Chemical composition of soils. 

Inert ingredients in per cent, of dry soil. 











Beown 






Insoluble 


Soluble 


Sor>A- 


Oxide of 


Peroxide 




Residue. 


Silica. 






Man- 


OF Iron. 












ganese. 






Sand. 


Clay. 


Sand 


Clay. 


Sand 


Clay 


Sand 


Clay. 


Sand 


Clay. 


Sand. 


Clay. 


93.630 


72.746 


1.682 


8.926 


.060 


.112 


.102 


.106 


.761 


12 406 


1.532 


2.473 


94.770 


73 690 


.486 


3.370 


.069 


.004 


.156 


.146 


.706 


5.989 


.733 


7 305 


93.362 


60.310 


1.721 


2.000 


.018 


.119 


.220 


.196 


.941 


9.709 


1.339 


18 066 


95.630 


73.422 


.879 


2.709 


.064 


trace 


.049 


.164 


.224 


4.054 


.473 


10.598 


92.090 


63.444 


1.220 


11.325 


.035 


.079 


.126 


.052 


.963 


3.894 


1.9.59 


13.454 


90.230 


77.860 


1.940 


1 790 


.009 


.041 


.313 


.056 


1.927 


5.fit6 


•Z.141 


7.538 


90.681 


54.565 


1.885 


13 219 


.130 


.277 


.172 


.079 


1.837 


7.089 


1.436 


16.071 


92.460 


51.063 


1.550 


20.704 


.036 


.325 


.010 


.119 


.843 


5.818 


2.649 


10.539 


94.428 


79.580 


.529 


3.628 


.069 


.065 


.101 


.195 


.661 


3.420 


1.195 


4.988 


94.822 


75.350 


1.037 


7.310 
7.498 


.022 


.2.D8 


.020 


.038 


.930 


5.784 


1.576 


5.567 


93.210 


68.209 


1.293 


.051 


.128 


.130 


.115 


.979 


6.381 


1.503 


9.660 




91.498 




1.722 




.054 




.066 




1.372 


1.522 



SWAMP AND LOESS SOILS. 



Hu- 
mus. 


Loess. 


Hu- 
mus. 


Loess. 


Hu- 
mus. 


Loess 


Hu- 
mus. 


Loess 


Hu- 
mus. 


Loess 


Hu- 
mus. 


Loess 


35.886 


68.853 


20 825 


4.918 


.109 


.165 


.098 


.164 


7.010 


3.569 


14.476 


2.812 



SOILS COMPARED WITH THEIR SUB-SOILS. 

SOILS. 



Sand. 


Clay. 


Sand 


Clay. 


Sand 


Clay. 


Sand 


Clay. 


Sand 


Clay . 


Sand. 


Clay. 


93.222 


73.978 


1.019 


5.034 


.072 


.085 


.124 


.133 


1.162 


5.205 


1.145 


6.998 











SUB-SOILS. 












90.714 


66.290 

-i-7.688 


2.212 


7.446 


.064 


.085 


.080 


.125 


1.739 


6.947 


2.276 


12.086 


-1-2.508 


-1.193 


-2.412 


-H.008 


.000 


-H.044 


-1-.008 


-.577 


-1.742 


-1.131 


-5.088 



ARID AND HUMID SOILS COMPARED. 



Hu- 
mid. 


Arid. 


Hu- 
mid. 


Arid. 


Hu- 
mid. 


Arid. 


Hu- 
mid. 


Arid. 


Hu- 
mid, 


Arid. 


Hu- 
mid. 


Arid, 


84.031 


70.565 


4.212 


7.266 


.091 


.264 


.133 


.059 


3.131 


5.752 


4.296 


7.888 



times as much magnesia as do the humid soils with which 
they have been comj)ared. They also contain some more of 
each of the other essential plant foods except sulphur, the 
sulphuric acid being less. 

If, however, a comparison is made between the arid soils 
and the mean of the 10 clay soils given in the first table, 
it wall be seen that, excepting potash, lime and magiiesia, 
these contain more of the essential ingredients of plant 
food than do the arid soils, and so, too, there is more solu- 
ble silica. 

88. Humus. — It is this product in the soil which gives to 
it usually its dark color, but so far as its chemical composi- 
tion is concerned its nature is not yet well understood. It 
is a very important ingTedient of fertile soils and is the 
product of decaying organic matter. 

In torrid climates where the soil is warm the whole year 
and in arid regions where the soil is more open on account 
of deficient moisture as well as on sandy soils wherever 
found, the rate of complete decay is so rapid that the 
amount of humus is generally relatively small ; but in tem- 
perate climates, where the soil is damp, its texture close and 
rains frequent, the organic matter decays more slowly and 
the amount of humus in the soil is relatively greater. 

The great importance of humus in agricultural soils is 
found in the fact that it is relatively insoluble under good 
field conditions and does not leach away and in- this form 
becomes the food of niter-forming germs which convert it 
by degrees into nitric acid, as one of their waste products, 
but the essential form of nitrogen for the food of most 
higher plants. A soil entirely devoid of humus must neces- 
sarily be manured or given nitrogen in some other form 
in order to make it fertile. 

89. Difference Between the Humus of Arid and Humid Cli- 
mates. — Tlilgard and Jaffa have made the important dis- 
covery that the humus of arid soils is relatively richer in 
nitroffen than is that of humid soils and hence that smaller 



77 



amounts of it will inoet the needs of niter-fovming germs 
and thus allow large crops to be produced where, with a 
poor form of humus, this would be impossible. 

The results of their studies in this line are stated in the 
table below : 





No. of 

samples. 


Humus in 
soil. 


Nitrogen 
in humus 


Humic 

nitrogen in 

soil. 




18 
8 
8 


Per cent. 

.75 

.99 

3.01 


Per cent. 

15.87 

10.03 

5.24 


Per cent. 
.101 




.102 




.132 







In speaking of these results they say, "It thus appears 
that, on the average, the humus of the arid soils contains 
three times as much nitrogen as that of the humid, that in 
the extreme cases the nitrogen percentages in the arid hu- 
mus actually exceeds that of the albuminoid group, the 
flesh-forming substances." 

^'It thus becomes intelligible that in the arid region a 
humus percentage, which, under humid conditions, would 
justly be considered entirely inadequate for the success of 
normal crops, may, nevertheless, suffice even for the more 
exacting crops. This is more clearly seen on inspection of 
the figures in the third column, wdiich represent the product 
resulting from the multiplication of the humus percentages 
of the soil into the nitrogen of the humus." 



90. Chemical Composition of Soils Compared With the 
Rock from Which They Are Derived. — When a soil accumu- 
lates in place from slow decomposition of the underlying 
rock there is sometimes a close resemblance in chemical 
composition between the rock and the derived soil, but in 
other cases there is little resemblance between them. If 
the rock is made up of a large percentage of relatively solu- 
ble materials, as is the case ^vith most limestones, then the 
solvent power of water, combined with the effects of leach- 
ing, tend to cause a concentration of the relatively insoluble 



78 



ingredients, thus giving rise to a soil very different in chem- 
ical composition from the parent rock. 

If, on the other hand, the rock is made up of minerals of 
nearly eqnal solubilities, or if in any way the soil results 
from a mechanical breaking up of the rock, then the soil 
may have much the same relative amounts of ingredients as 
the parent rock shows. In the table which follows are 
given the composition of some rocks and of soils derived 
directly from them : 



Composition of rocks and residual soils. ^ 





Trenton 
Limestone 


Bermuda 
Limestone 


I 
Gneiss, 


Granite. 


DiORITE. 




Rock 


Soil. 


Rock 


Soil. 


Rock 


Soil. 


Rock 


SoU. 


Rock 


Soil. 


Silica (Si02) .... 
Alumina (AI2O3) 
Ferric oxide. . . . 


Prct. 

.44 

.042 


Prct. 

43.07 
25.07 
15.16 
0,63 
0.03 
2.50 
1.20 
tr. 


Prct. 

.052 
54 

54 '.496 
1.751 
0.066 
0.252 

44.251 


Prct. 

45.16 

15.473 
13.898 
3.948 
0.539 
0.133 
0.007 
2.533 


Prct. 

60.69 
16.89 
9.16 
4.44 
l.Od 
4.25 
2.42 


Prct. 

45.31 
26 55' 
12.18 
tr. 
40 
1.10 
0.22 
0.00 
0.47 

13 75 


Prct. 

69.33 
14.33 
3.60 
3.21 
2.44 
2.67 
2.70 


Prct. 

65.69 
15.23 
4.39 
2.63 
2.64 
2.00 
2.12 


Prct. 

46.75 
17.61 
16.79 
9.46 
5.12 
0.55 
2.56 
00 
0.25 

0.92 


Prct. 

42.44 

25.51 
19 20 


Lime (CaO) 

Magnesia (MgO; 
Potash (KjOj ... 
Soda (NaaO).... 
Carbon dioxide.. 


34.77 
tr. 
not d. 
notd. 
42.72 


0.37 
0.21 
0.49 
0.56 
0.00 


Plios. acidiP.jOs" 


0.10 
11.22 


0.06 
4.70 


0.29 


Water and vola- 
tile products . . 


l.OS 


12.98 


.328 


18.265 


.62 


10.92 



The two limestones, it will be seen, have given rise to a 
soil containing almost as much silica, alumina and iron 
oxide combined as is contained in the three soils from the 
other three kinds of rock, the per cents, standing, in round 
numbers, 83, Y5, 84, 85 and 87. In other words there is 
a strong tendency to bring all soils approximately to one 
composition. Indeed it may be said that in any soil the 
essential ingredients of plant food make up but from 3 to 
8 per cent, of the total dry weight. It will be observed 
that in the case of the soil derived from the Bermuda lime- 
stone, not less than 98 pounds of every 100 pounds of rock 



1 Rocks, Rock Weathering and Soils. Merrill. 



79 



are dissolved and carried away l)y the water for each 2 
pounds of soil formed, the chief materials carried away 
beinc; the lime, maoiiesia and carhon dioxide. 



91. Amount of Essential Plant Food Removed from the 
Soil by Crops. — It is very important, in the management of 
soils, to know something of the draught upon them which 
crops of different kinds make, and in the table which fol- 
lows is given the amount of materials removed from the 
soil in 1,000 pounds of fresh or air-dried product. 

Table of amount of plant food in lOOo lbs. of air-dried liroduct. 

(WOLFF.) 





Maize. 


Oats. 


Wint'e 


Spring 


Wint'h 




Red 








Wheat 


Wheat 


Eye. 




Clover 




i 


a 


i 


a 


i 


d 


fe 


CI 


i 


a 


i 


d 


5; 


a 




ca 


ca 


2 


ctf 


f. 


CS 


CS 


? 


cfl 


C8 


CS 


CS 


ctf 


CS 
















£ 














u 




7J 


CiJ 


61.6 


26.7 


46.0 


16.8 


38.1 


18.3 


CO 
■38 2 


17 9 


45.9 


22 3 


m 
P7 6 


O 


Total ash 


45.3 


12.4 


38 3 


Potash (KoO) ... 


16.4 


3.7 


16.3 


4.8 


6.3 


5.2 


11.6 


5.6 


8.6 


5,8 


10,7 


4.7 


18,6 


13,5 


Soda (NaaO) ... 


.5 


0.1 


2.0 


1.0 


0.6 


0.3 


1.0 


0.3 


7 


3 


1.6 


0,5 


1 1 


4 


Magnesia (MgO) 


2.6 


1.9 


2.3 


1.9 


1.1 


2.0 


0.9 


2.2 


1.2 


2.0 


1.2 


2.0 


6.3 


4.9 


Lime (CaO) 


4.9 


0.3 


4.3 


1.0 


2.7 


5 


2 6 


0.5 


3,1 


5 


3 H 


6 


?0 1 


•,^,5 


Phos acidiPjOst 


;i8 


5.7 


2 H 


6.S 


2.2 


7.9 


2.0 


9.0 


2 5 


8.5 


1.9 


7 8 


5.6 


14 5 


Sul. acid CSOa).. 


2 4 


0.1 


2.0 


0.5 


1.1 


0.1 


1.2 


0.2 


1 6 


0.2 


1.8 


0,4 


1.9 


9 


Suipllur 


3.9 


1.2 


1.7 


1.7 


1.6 


1.5 






0.9 


1.7 


1.3 


1.4 


2 1 




Nitrogen 


4.8 


16.0 


5.6 


17.6 


4.8 


20.8 


5.6 


20.5 


4.0 


17.6 


6.4 


16.0 


19.7 


30 5 







From this table it appears that each ton of clover hay 
withdraws from the soil 30.4 11)S. of nitrogen; 37.3 lbs. of 
potash ; 12.6 lbs. of magnesia ; -40.2 lbs. of lime ; 11.2 lbs. of 
phosphoric acid; and 14.2 lbs of sulphuric acid, making 
an ac'CTco-ate of ash ingredients alone of 154.S lbs. 



92. Amount of Plant Food in an Acre-foot of Soil. — If we 
take 4,000,000 pounds as the dry weight of an acre-foot of 
all soils, except the humus and that at 2,000,000 (149), 
and the percentages of essential plant food given in the 
tables on pages 74 and 75, the amount of plant food per 
acre-foot may then be computed, giving the results in the 
table below : 



80 



Table giving the tons of essential 2olant food per acre-foot 
of different types of soil. 



Potash (KoO) 

Lime (CaO) 

Magnesia (MpO) 

Phosphoric acid (P3O5) 
Sulphuric acid (SO3 ) . . . 



Sandy soil, 



Tons. 

2.42 
1.70 
.96 
1.74 
1.10 



Clay soil. 



Tons. 

6.38 
12.34 
9.12 

2.82 
1.50 



Loess soil, 



Tons. 

8.70 
116.40 
73.84 
4.00 
1.80 



Humus 
soil. 



Tons, 

6.39 
37.86 
8.68 
1.50 
1.48 



From this table it appears that the amount of plant food 
per acre-foot of iield soils, not including nitrogen, ranges 
from abont 2 to S tons of potash, 2 to 11(3 tons of lime, 
1 to 73 tons of magnesia, 2 to 4 tons of phosphoric acid, 
and 1 to 2 tons of sulphuric acid. 



93. Number of Crops Required to Remove the Plant Food 
of an Acre-foot of Soil. — ^rhc ratio (»f dry weight of the ker- 
nels to that of the straw and chatf in a crop of wheat has 
been found to be as 1 to 1.1 in a dry season, but to be as 
high as 1 to 1.5 when there has not been an undesirable 
stimulation to the growth of straw. Taking this ratio of 
1 to 1.5, a yield of 40' bushels of wheat per acre would 
mean a crop of 2,1:00 lbs. of grain and 3,600 lbs. of straw. 
From these two figures, the data in the table of (91) and 
that of (92), it is possible to compute the number of crops 
of wheat yielding 10 bushels per acre which would remove 
the amount of plant food in an acre-foot of one of the sev- 
eral types of soil represented in the table of (92). Solv- 
ing the problem for the potash in the clay soil the case 
would be 



6.38 X 2,000 



(2.4X5.2) + (3.6X6.3) 



362.9 



81 

where 6.38 is the tons of potash per acre-foot, 
2,000 is the number of lbs. in one ton, 
2.4 is the number of 1,000 lbs. of grain in 40 bush, of wheat, 

5.2 is the nvimber of lbs. of potash per 1,000 lbs. of grain, 
3.6 is the number of 1,000 lbs. of straw with 40 bush, of wheat, 

6.3 is the number of pounds of jjotash per 1,000 lbs. of straw, 
362.9 is the number of crops of wheat. 

When the j)robleiii is solved for each of the essential 
plant foods used bv the wheat crop, the results will stand 
for the clay soil as given below : 

Potash enough for 363 crops of wheat of 40 bush, per acre. 
Magnesia enough for 2,082 crops of wheat of 40 bush, per acre. 
Lime enough for 2,260 crops of wheat of 40 bush, per acre. 
Phosphoric acid enough for 210 crops of wheat of 40 bush, per 

acre. 
Sulphuric acid enough for 108 crops of wheat of 40 bush per 

acre. 
Nitrogen enough for 78.5 crops of wheat of 40 bush, per acre. 

In computing the nitrogen in the soil for this table .132 
l^er cent., from the table in (89), was taken and the same 
weight of soil, 4,000,000 pounds per acre-foot as used for 
the other plant foods. 

It has been assumed that 10 bushels of grain and 3, GOO 
pounds of straw per acre are taken from the ground each 
crop and that nothing is returned to the soil, and yet chem- 
ical analyses would indicate that there is enough of every- 
thing but nitrogen for more than a century of cropping, 
and this is saying nothing regarding the plaut food which 
is known to exist in the second, third and fourth feet of soil 
in which the roots of plants regularly feed. Plainly we 
have very important knowledge yet to discover regarding 
the feeding of plants from the soil. 

94. Experiments at Rothamstead. — The classic experi- 
ments which have been made by Sir J. B. Laws and his as- 
sociates regarding the conditions which determine the fer- 
tility of the soil, have thrown much needed light upon this 



82 

problem. By growing the same crop year after year on the 
same ground to which no nitrogen-bearing manures were 
applied, they learned that when fertilizers containing the 
essential ash ingTcdients of the plant were added to the 
soil larger yields and more nitrogen could be taken from 
the ground. 

They found that when wheat grown continuously for 32 
years on the same soil without manure of any sort could 
obtain but 20.7 lbs. of nitrogen ^Der acre, the same crop on 
adjacent and similar land given fertilizers without nitrogen 
could gather 22.1 lbs. or Q.76 per cent. more. Barley, 
which, with no fertilizers, during 24: years could gather but 
18.3 lbs. per acre per amium, did, when aided with other 
ash ingredients, remove from the soil 22.4 lbs. of nitrogen 
per acre. Beans, which gathered from untreated land 31.3 
lbs. of nitrogen per acre during 24 years, took off from the 
land under the other treatment 45.5 lbs. per acre. So, 
too, in a rotation of crops, 7 courses in 28 years, no fertil- 
izers gave 36.8 lbs. of nitrogen, while with superphosphate 
of lime the yield was 45.2 lbs. per acre. Again in the 
mixed herbage of grass land 20 years without fertilizers 
gave 33 lbs. of nitrogen per acre, but Avhere mixed mineral 
fertilizers containing potash were given the yield was 55.6 
lbs. of nitrogen per acre. 

95. Store of Nitrogen in the Soil. — The mean amount of 
nitrogen in eleven arable and grass soils at Bothamstead is 
placed by Laws and Gilbert at .149 per cent, and for eight 
other Great Britain soils at .166 per cent. Voelcker found 
in four Illinois prairie soils .308 per cent., and C. Schmidt 
gives for seven rich Russian soils .341 per cent. The 
mean of these 30 analyses is .219 per cent, and yet a soil 
containing but .1 per cent, will carry 4,000 lbs. or enough 
for nearly 60 40-bushel crops. 

96. Amount of Nitrogen in Four Manitoba Soils. — As an 

example of soils exceptionally rich in nitrogen the table 



83 



below gives tlio distribution and amount per acre in each 
of the upper four feet of four Manitoba soils : 





Niverville. 

•• 


Brandon. 


Selkirk. 


Winnipeg. 


First foot 


Lbs. 

7,308 
5,408 
2,484 
1,520 

16,720 
8.36 


Lbs. 

5,236 

3,488 

2,592 

870 

12,186 
6.093 


Lbs, 

17,304 

8,448 
2,736 

1,487 


Lbs. 
11,984 




10, 464 


Third foot 


5,688 




4,045 






Total 


29,975 
14.987 


32, 181 


Tons 


16.09 







Tlius it is seen that in the upper four feet of these rich 
soils there was found from to 16 tons per acre of nitrogen. 

97. Forms in Which Nitrogen Occurs in the Soil. — JSTitro- 

gen occurs in the soil in several distinct forms : 

1. In humus, deseril)ed in (88), wdiich is by far the most 
important form and the substance which carries the largest 
proportion of that which the soil contains. 

2. In organic matter in the form of roots, stubble and 
farmyard manure, which by slow degrees is converted into 
humus to make good that which has been used. 

3. As free nitrogen in soil-air which is seized upon by 
some forms of microscopic life described in (101) and con- 
verted into organic form for their use. 

4. As nitrates of lime, magnesia, potash and soda, and 
this is the form from which most of the higher plants get 
their supply. 

5. As ammonia, nitrous acid and nitric acid, which are 
transition stages to one of the nitrates named above and 
which are formed either from the humus or organic matter 
or are brought down with the rain. "^ 

98. Distribution of Nitrogen in the Soil. — In humid cli- 
mates the largest amount of nitrogen is found in the surface 
6 to 1'2 inches, but as already shown in (96) large quan- 
tities are found as deep as four feet below the surface. 



84 



Warrington determined the distribution of nitrogen in 
some of the Rothamstead soils to a depth of 9 feet in 9-inch 
sections. The resuhs he found are given in the table be- 
low : 

Nitrogen in soils at various depths. 





Arable soils. 


Old pasture. 




Lbs. per acre 

3,015 
1,629 
1,461 
1,228 
1,090 
1,131 

7,333 
4,365 
4,559 

16,257 


Lbs. per acre 
5,351 




2,313 




1,580 




1,412 




1,301 




1,186 




10,656 










Total 









In these two cases the nitrogen decreases downward until 
about four feet and below this depth to nine feet the 
amount remains nearly constant. It will be seen that the 
amount is very large in the aggregate. Enough for more 
than 240 crops of wheat, 40 bushels per acre, could it all 
be used. 

99. Amount of Nitric Acid in Soils. — The amount of the 
available nitrogen in soils, or nitric acid, is seldom a large 
quantity and while crops are growing the quantity is still 
smaller. 

Warrington states that the nitric nitrogen in the soil 
seldom reaches 5 per cent, of the total amount present, and 
in the surface three feet of the arable soil referred to in 
(98) this would represent 366.6 lbs. of nitric nitrogen and 
1,650 lbs. of nitric acid per acre; enough, if it could all be 
used, to give a yield of 57.5 bushels of wheat per acre. 

100. Nitric Acid in Fallow Ground. — The amount of ni- 
tric acid in fallow ground was determined to a depth of 4 



85 



feet in one-foot sections on May 24 and again on Ang. 22, 
and the resnlts are given in the table below : 

JVitric acid in fallow ground in pounds per acre. 





1st foot. 


2nd foot. 


3rd foot. 


4th foot. 


May 24 


78.03 
293.72 


21.43 
116.17 


8.13 
23.50 


4.76 


August 22 


16.72 








215.69 


94.74 


15.37 


11.96 







These figures are a mean of the ainonnts fonnd in nine 
different snb-plots, the soil being a clay loam changing into 
sand in the third foot. It will be seen that the total ainonnt 
of nitric acid at the close of May was 112.35 lbs., contain- 
ing 24.97 lbs. of nitrogen, enongh for only abont 14.3 
bnshels of Avheat. On the 22nd of Angnst, however, there 
had been an increase to 450.11 ll)s. per acre, containing 
100.02 lbs. of nitrogen, enongh for nearly 60 bnshels of 
wheat per acre. 

101. Source of Soil Nitrogen. — Until recently it was 
inaintain{'<l tliat the nitrogen for the growth of all plants 
was derived from the linnms of the soil and from the small 
amonnt of ammonia and nitrons and nitric acids bronght 
down by the rains. It is now known that the free nitrogen 
of the atmosphere is the nltimate sonrce of soil-nitrogen, 
and that the soil-nitrogen is being continnally retnrned to 
the air again jnst as was long ago recognized to be the case 
with the carbon of living forms. 

1. The immediate sonrce of hnmic nitrogen is the slow 
decay of organic matter, whether this be the roots, stems or 
leaves of plants or the tissnes and waste products of ani- 
mals, and a large part of the life processes of the world 
take place between the conversion of hnmns into living tis- 
sues and dead tissues back into humus again. 

2. The formation of nitrous and nitric acids through an 
oxidation of the nitrogen of the air by electrical discharges 

5 



86 



such as occur during thunder storms is generally conceded. 
It is also thought that a part of these combinations may be 
brought about through the action of ozone upon ammonia. 
Warrington is also of the opinion that the peroxide of hy- 
drogen in the air causes the conversion of some atmospheric 
ammonia into nitric acid, and hence that not all the nitric 
acid brought down by the rains was formed as new ma- 
terials in the atmosphere from direct union of oxygen and 
nitrogen gases. 

The amount of nitrogen brought to the soil with the rains 
seldom equals 5 lbs. per acre per annum in the open coun- 
try, as shown by the following table : 



Nitrogen as ammonia and nitric acid, in pounds per acre 
jjer annum, in rain. 



Hothamsted, 
8 years. 


Lincoln, 

New Zealand. 

3 years. 


Barbadoes. 
3 years. 


Nitro;?en as ammonia 


Lbs, 

2.53 

0.84 


Lbs. 

0.74 
l.OO 


Lbs. 
93 


Nitrogen as nitric acid 


2.84 




3.37 


1.74 


3.77 




FiG- 25.— Showing the influence of free-nitrogeu-fixing germs on the growth of 
peas. The )arge plants all grew in sand containing tlie nitrogen-fixing bac- 
teria, while tlie small plants grew in soils identically the same except that 
all bacteria were excluded from them. After Hellriogell. 



i7 



These amounts, it will be seen, are far too small to be of 
great importance to plant life. 

3. The process of symbiosis is a third method by which 
the nitrogen supply of the soil is maintained and next to 
the decay of organic matter is the most important of any 
yet w^ell understood. It was in 1888 that Hellriegel pub- 
lished the results of his studies, which thoroughly estab- 
lished the fact that great numbers of microscopic forms of 
life inhabit the roots of leguminous plants, forming upon 



mfilij 




Fig. 26.— Showing the growth of rye, oats, peas, wheat, flax and buckwheat in 
soils fertile in all elements of plant food except nitrogen, and illustrating the 
power of the pea, through its root tubercles, to procure nitrogen from the 
air. Alter P. Wagner. 

them tubercles in which these organisms live and withdraw 
free nitrogen from the soil-air for their needs. It had long 
been known to farmers that in some way clover in rotation 
with other crops left the soil richer in nitrogen, and it is 
now known that the bacterium which lives on the clover 
roots, deriving a part of its food from the clover plant, at 
the same time increases the nitrogen supply available to the 
clover crop and so we have two fVtrms of life living together 



88 



in what lias been named symbiotic relations. There are 
other forms of bacteria Avhicli live njion the bean, pea, lu- 
pine and other members of this family, also having the 
power of lixino' free nitrogen from the soil-air in forms 
available to higher plants. 

It is known that other forms of bacteria live in symbiotic 
relation with soil algae and in this way increase the sup- 
ply of soil nitrogen as shown by Frank, Schlosing, Jr., and 
Laurent in 1891, followed by Kosswitsch in 1894; and the 
great demands for the fixing of free nitrogen to make good 
the rapid return of it to the air and loss in drainage waters 
appears to call for other agencies than those named. 



1,1 



^m^ 




Fifi.^ 2i.— Sliowiiij;- njits fiidwiiis under ((UHlitioiis identical -with those of 
Fig. 19. except tliat tile several pnts re<'eived Chile saltpetre. 1, 2 
and 3 grams resjiectively, thus enforcing tlie immense importance to 
such plants of nitric nitrogen. After 1'. Wagner. 



4. Winogradsky has shown that there is a form of bacil- 
lus in the soil which, when supplied Avith sugar and iso- 
lated from the influence of oxygen, is capable of thriving 
and fixing free nitrogen from the air, and this discovery 
may lead to a knowledge of still a fourth mode of increas- 
ing the world's supply of nitroe;en. 



89 



Some of Bertlielot's experiments are tlioiialit l)y him to 
show that soils destitute of all visible vegetation may gain 
large quantities of nitrogen when simply exposed to the air, 
and he thinks he has realized gains as large as 70 to 130 lbs. 
of nitrogen per acre in 11 weeks. Such conclusions, how- 
ever, require careful verification as they are at least ap- 
parently conti'adictod by field practice. 

102. Nitrification. — 'rho formation of nitrates in the soil 
involves at least four distinct phases or stages: (1) the am- 
monia stage, (2) the nitrous acid stage, (3) the nitric 
acid stage and (4) the nitrate forming stage. Wlien 
humus or dead organic matter is placed under the right 
conditions of temperature, moisture and air in the pres- 
ence of ammonia-forming germs, these organisms feed 
upon portions of it and throw oft" ammonia as a waste ]n"od- 
iict. Ammonia is extremely soluble in water and is re- 
tained by it in large volumes. Even dry soil has the 
power of condensing and retaining it. In a fertile soil 
where ammonia has been formed there are also present 
nitrous acid germs which are able to use ammonia in their 
life processes but throwing off nitrous acid as a waste prod- 
uct. The niter germs or "mother of petre" utilize the 
nitrous acid in their work and throw off as a by-product 
nitric acid. This nitric acid readily attacks any of the 
bases in the soil which are held by carbonic and other weak 
acids, displacing them and forming nitrate of lime, mag- 
nesia, potash or soda, as the case may be. 

In the old days of "niter farming," when nitrate of 
potash for gunpowder was obtained from the soil, great 
pains were taken to form a soil rich in organic matter and 
to keep it warm, well su]:)])lied with moisture and thor- 
oughly aerated. These, too, are the points to be secured in 
the best management of soil for farm and garden crops. 

103. Denitrification. — Pitted against the i)rocesses of fix- 
ing free nitrogen from the air, which have been described, 



90 

there are other processes which reverse these operations and 
set free again the nitrogen of organic coniponnds and of ni- 
trates so that it is again returned to tlie atmosphere as free 
nitrogen gas. 

(1) Dr. Angus Smith sliowed in 1S6T that nitrates in 
sewage waters are decomposed and the nitrogen set free 
as a gas. (2) Schlosing showed that when moist hnmns- 
bearing soils are jjlaced in an atmospliere free from oxygen 
thej quickly lose all traces of nitrates. (3) Warrington 
demonstrated that sodium nitrate in a Avater-losrffed soil 

• T Oct) 

IS decomposed and the nitrogen liberated as a gas. (4) 
So great is the demand for oxygen in rich water-logged 
soils that according to the experiments of Miintz even such 
compounds as chlorates, iodates and bromates are deprived 
of their oxygen, leaving iodides, chlorides and bromides in 
their place. (5) When black marsh soils are stirred up 
with water and allowed to st^nd Prof. J. A. Jeffery and the 
writer have shown that the nitrates rapidly disappear and 
nitrogen gas is set free. 

In all of these cases there are microscopic organisms in 
the soil and water whose needs for oxygen are so great that 
when that which is free in the soil-air or water-air is not 
sufficient they have the power of decomposing nitrates and 
even some organic compounds for the oxygen they contain 
and in this way liberate free nitrogen. 

(6) There is still another condition under which denitri- 
fication takes place in which the loss is large, rapid and 
nearly complete. It is when human excrements are covered 
with pulverized dry soil, as is done in the dry-earth closets. 
The late Colonel Waring kept two tons of dry earth for a 
number of years, having it used over and over again in or- 
der to see how long it might be used without losing its effi- 
ciency. The closets were filled with the dry earth and excre- 
ment about 6 times each year, and when they were emptied 
the material was thrown in a heap on a floor of a well venti- 
lated cellar to dry. After the same soil had been used over 
not less than 10 times it was analyzed for the amount of 
nitrogen it contained, and in 4,000 lbs. of the soil was found 



91 

no more than 11 lbs. of nitrogen and yet not less than 230 
lbs. had been added to it and the soil at the start contained 
at least 3 lbs. There had been set free therefore 

230 — 8 = 222 lbs. of nitrogen. 

'Nov was this all, for so completely had all the carbonaceous 
materials been oxidized that even the paper used had en- 
tirely disappeared. 

How far these processes take place under field condi- 
tions when farmyard manure is applied we have yet to 
learn. 



92 



CHAPTER III. 
SOLUBLE SALTS IN FIELD SOILS. 

All the food of plants is taken bv them in the form of 
liquids or of gases, and hence the fertility of a soil must be 
determined by the rate at which plant food may be dis- 
solved in the soil water and carried to them at the time the 
crops are growing. If the ash ingredients and the nitro- 
gen used by plants while growing are supplied in the soil 
water as rapidly as the crop can use tlu^n, then maximum 
yields will be certain if the temperature and sunshine are 
also right. 

104. Amount of Soluble Salts in Field Soils. — There is a 
very wide difference in the amount of salts dissolved in 
soil water under diffe'rent conditions. In arid regions, 
where there is little soil leaching, the salts become in places 
so abundant that plants are unable to grow and alkali 
lands are the result. In humid climates, especially where 
the soils are sandy, the salts may be so small in amount 
that plants starve. In the table Ix'low these differences 
are shown for the surface foot. 



Lbs. per million of dry soil 

Lbs. per acre of 4,000,000 

lbs 



Water soluble salts in soils 
of arid climates. 



Where bar- 
ley will not 
srow. 



S,585 
a4.340 



Where bar- 
ley grows 
4 ft. high. 



4,877 
15,508 



Water soluble salts in soils 
of humid climates. 



Fertile clay 
loam. 



272 

1,088 



Poor sandy 
soil. 



These figures show a range of total salts soluble in water 
from 17 tons per acre foot to less than .05 tons. 



9' 



105. Maximum Amount of Water Soluble Salts Which 
Limit Plant Growth. — liil^Liard conchKlcs from liis studies 
that the iiiaxinniin niiioiint of soluble alkali salts which are 
consisteut with a full ('ro|) of barley hay is 25,000 to 
32,000 lbs. ])('!• acre in the surface four feet of soil, pro- 
vided this is not more than one-half its weiiiht sodium car- 
bonate. 

Whitney places the limit of possible plant production 
in the soils of the Yellowst(nie Park at 15,000 lbs. per 
acre in the snrface foot, where the black alkali or sodium 
carbonate is absent. 

Grapes grow in Algeria in alkali soils containing GOO 
lbs. per million of dry soil but die when it reaches 1,700 
lbs. per million in the surface soil and o,700 in the sub- 
soil ; bnt grain crops grow normally when the soil contains 
2,000 ll)s" per mil Hon. 

106. Why too Much Soluble Salt in Soil Kills Plants. — De 
Vries found, as represeutcMl in Kig. 2S, that when the liv- 




Fi(!. 2.S.— SlKaviiii: til 



'(•1 !if too Stroll-- 
pl.'isiii of l)l;ilir I 



ing cells of a ])laut were inuuersed in a 4 per cent, solution 
of ])otassiuni nitrate, there was first a shrinkage in V(dume 
through a loss of water, as shown between 1 and 2. A\'hen 
the solution was given a strength of <> })er cent, the ju'oto- 



94 

plasmic lining, p, began to shrink away from the cell wall 
h., as shown at 3, and when the strength of the solution Avas 
made 10 per cent., the conditions shown in 4 are produced. 
Wlieji the cells of plants are affected in this w^ay they wilt 
and growth ceases. 

A soil containing 20 per cent, of water and also 2,000 
lbs. of water soluble salts per million of dry soil would 
contain 2,000 lbs. in 200,000 lbs. of water or 1 part in 200, 
which is .5 per cent. If the soluble salts constitute 2 per 
cent, of the dry weight of the soil then with 20 per cent, of 
moisture present the strength of the soil solution would be 
ecpial to that which De Vries found fatal to plants, or 10 
per cent. 

The salts in the surface three inches of soil upon Avhich 
Hilgard found barley to grow four feet high were 1.2 per 
cent., wdiile it was 2.44 per cent, in the same level where 
the barley died. With 20 per cent, of moisture in the soil, 
and all the- salts dissolved, the soil solution in the first 
case would represent a strength of 6 per cent, and in the 
second ease 12.2 per cent., Avhich is larger than the amount 
De Vries found fatal. 

107. Concentration of Salts in Zones. — Where long contin- 
ued drought has occurred in soils rich in soluble salts the 
tendency is for the salts to collect in the surface two or 
three inches and in this M-av become injurious to plants 
when they would not be so with an abundance of w^ater in 
the soil. 

When heavy rains follow such a concentration of salts 
at the surface, or if the land is irrigated so as to produce 
percolation, the result is to wash the salts down in a body 
to the depth reached by j)ercolation, and hence it may hap- 
pen that a layer of soil very rich in salts may occur at the 
surface at one time and later at a distance of 12, 18, 24 or 
30 or more inches below, determined by the depth of per- 
colation. 

108. Origin of Soluble Salts. — The excessive amounts of 
salts found in alkali lands are usually the result of long 



95 

coiitiniu'd rock deeav under conditions where little or no 
leaching' has taken place. Rains enongli fall to produce 
decay, bnt not enongh to carry the salts formed into the 
drainage channels and ont of the conntry. This is why 
alkali lands are largely peculiar to desert or semi-arid 
climates. 

109. Leaching- Necessary to Fertile Soils. — It is clear 
from 106 and 108 that if there was not some leaching to 
take np and carry away the extremely solubl.e salts not 
availalde as plant food all soils would in time become "al- 
kali lands ;" so that while excessive leaching is undesirable, 
a sufficient amount is indispe-nsable. 

The prevention of the accumulation of undesirable solu- 
ble salts in the soil of irrigated lands in dry climates is one 
of the most serious of jn-aetical problems. 

110. Soluble Salts in Marsh Soils. — The black marsh soils 
of humid climates often contain unusually large amounts 
of soluble salts, sometimes reaching 2,366 parts per mil- 
lion of the dry soil in the surface 6 inches after maturing 
a crop. This would make the water contain 1.18 per cent, 
of salts if the water content of the soil was 20 lbs. per 100 
of dry soil. Many of these soils behave much like alkali 
lands, being unproductive, the crops often dying when 
there is no evident reason for it. 

111. Correction for Alkali Lands. — It has been found that 
when a soil is unproductive from too high a per cent, of 
sodium carbonate or black alkali and there is not enough 
of other soluble salts to be injurious, this may be corrected 
in part by the use of gypsum or land plaster, which has the 
effect of converting the carbonate into the sulphate or 
"white alkali," like amounts of which are less harmful. 

It often happens that waters which must be used in irri- 
gation contain black alkali, and where this is the case it is 
Avell to correct the water by using land plaster in the reser- 
voirs or distributing canals, for the water to run over or 
through, before reaching the field. 



96 




Fiu 



29.--Sh(>\vinjr the seasonal f)ianj;es in (lie Mimniiits of nitrates in the 
soil under irrowiuK' corn. 



97 




l-"l';. 3ii. — SlKiwin.n' liic scnsiiii.il cli.-ii 
ill tile suil iimh 



iH'cs ill tile MllHiillits of 
•1- jiTowinK i-iii-ii. 



ihible 



98 

112. Drainage the Ultimate Remedy. — Drainage must be 
tlie ultimate remedy for any alkali land, as it can be only 
a matter of time when any fertile soil will develop enough 
undesirable soluble salts to render it sterile or less produc- 
tive, unless the soluble salts not needed are removed, and 
only drainage can do this. 

113. Deep and Frequent Tillage Helpful. — It is clear that 
whatever means will prevent the exeessive evaporation of 
water from the surface wall in so far lessen the concentra- 
tion of salts there, and hence frequent and deep cultiva- 
tion, to form effective mulches, will lessen the rise of 
water, and therefore of salts, to the surface and in this way 
permit crops to be grown on soils which are critically near 
the limit of sterility on account of the high salt content. 

114. Change in Soluble Salts with Season. — In Figs. 29 
and ->0 ar(^ re|)resented the changes in the nitrates and total 
soluble salts in the surface four feet under three fields of 
corn, beginning with Aj^ril and ending with Sept. Re- 
ferring to th(? nitrate curves it wiM be seen that the nitrates 
start in April nearly equal in the four feet, but increase 
rapidly in the first foot until the middle of June, when 
the corn begins to draw^ on tlie supply. From this time 
they decrease rapidly until the middle of July, when they 
are less than in April and less than in the second foot. By 
the middle of August, when the crop has ceased to draw 
much but water from the soil, there is a slow increase again 
and then one more rapid after the corn is cut, Sept. 1. 

The change in the total salts is much less marked, but 
evident, there being a general decrease. The mean amount 
of salts at the beginning and at the end of the season are : 

April 18. Sept. 1. 

Total salts 540 363 

Nitrates 86 32 

Difference 454 331 

From these figures it appears that the salts, other than 
nitrates, have decreased during the season 123 lbs. i>ev mil- 
lion of the dry soil for the four feet, or 1,968 lbs. 



99 



115. Variation of Soluble Salts with Different Crops. — 

There is a marked ditt'ereiiee in the aniount of sohible salts, 
and es[)ecialJy in the amount of nitrates, in soils under 
crops like corn and potatoes, where inter-tillage is i)rac- 
ticed, and nnder such crops as clover and oats, where the 
ground is not cultivated at any time of the season. This 
is very clearly siiown in Fig. 82; tlio nitrates are plotted 
in the lower two sets of curves and the total soluble salts 
in the upper two sets. 

The nitrates in the first f<:)ot under the corn and potatoes 
increased rapidly until July 1st, when they were five times 
as concentrated as in the fourth foot ; but in oO days more 
the nitrates had been re<luced from over 400 llis. to 40 lbs. 
per acre. 



PARTS PER MILLION OF DRY SOIL. 




I^lG. 31.— Shows flic iiiciin jiiiKMiiil of iiiti'iilcs ninl lut.-il s.iliililc Siilts 
ill tlK? .siu-facc fiuir fcit ol' soil unilcr inltiv nicil ami noi cultivated 
cTni)s. 

In the ease of the uncultivated crops the fields started 
with about 40 lbs. per acre and increased to only 70, June 
1st, when they were highest; from this date they fell to 
little more than 10 lbs. per acre in the surface foot, but 
rose again to 60 lbs. at the end of August. 

With the total soluble salts there was at first a more 



LofC. 



100 




Fli;. ."-. Sh'iwiiii; llic dilTcri'iici lirl w ccii llir aninnnls cif uili-.-ili's ainl 
(i| Idl.-il soluiik' suits ia the soil ipmIci' ciilt haled and imi cidti vatud 

(•|-(I|)S. 



101 

r:i|)iil rise, from iicarlv -"XH) Ihs. |)(m- acre in the siii-f;u'<; foot 
on the cultix'iitccl iironiid April is, to alxuit ."iOO IKs. per 
acre, l)Ut falliiiiL!,' aiiiiin on Aiii;ust 1st to 2')i) ll>s. 

On the clover phjts the start was at 250 ll)s. j)er aci-e in 
the surface foot, risiiii;' to 21)0 llis. in 12 <hivs. I^'i-oni this 
<hite tliere was a slow decrease, fallini;' to 22<) ]|»s. on the 
(late when tlic cult ivatcil <;ronii(ls were hiiihest, at 600 lbs. 
})er aci'c. 

116. Relation Between Nitrates and Total Soluble Salts. — ■ 
As a i;'eneral rule when the nitric nitro^iicii in clav loams 
is very hiiiii the total soluble salts, as indicated by the 
electrical nu'thod, are very low. It will even ha])i)en that 
the electiMcal resistance will show but little more salts than 
are re(|nir(M| to a<'coniit tor t he nit rates, and this is ])erhaps 
Avhat should be expected for, if nitric acid is beinc,' formed 
m the presence of carbonates, these would he decomposed. 
to foi-ui nitrates, an<l if the rate of nitrification were suf- 
ficiently ra))id, it miiilit he that all rhe carbonates would be 
decomposed and little else hut nitrates left. 

idle rati<i <d' total soluble salts to nitrates in the surface 
foot of the ri\(' cnltix'atetl ficdds represented by the cnrves 
AViis a mean for t he season of 2. 1 4 to 1 , while in the snrface 
foot of the chtver fields it was 4.S to 1. 

For the second, third and fonrth feet tlie i-atio is 7.29 to 
1 for the corn and potatoes, and '.>.1»T to 1 for the clover, 
alfalfa and oats; and these ratios ai'c wduit would be ex- 
])ected it the loi'malioii of nitric aeid destroys the carbon- 
ates and bi-ea rhonates in the soil water. 

117. Closeness of Plant Feeding. — it was pointed <»uf in 
(7) wlnit small amounts of a fertilizer can he widely dis- 
tiMbnte(l through an aci'c of soil, and we ma\' now consider 
liow extremely (dose plants do feed the nitrates of a soil. 
In the table which follows are i;iven the amounts of ni- 
trates Avhich wei-e found in each foot of nine field plots, 
rejiresentec] by the cnrves, between .Inly IS aii<l Sei)t. 1. 

6 



102 



Table showincf mean amounts of nitrates under different crops 
between Julu IS and Sept. 1, in lbs. jier acre of dry soil. 





Plotl. 


Plot 2. 


Plot 3. 


Plot 4. 


Plots. 


Plot 6. 


Plot 7. 


Plots. 


Plot 9. 




Corn. 


Clover. 


Corn. 


Oats 

and 

clover. 


Pota- 
toes. 


Pota- 
toes. 


Clover. 


Alfalfa 


Corn. 


1st foot.. 
2nd foot. 
3rd foot.. 
4tli foot.. 


Lbs. 

50.94 
127.3.i 
83.52 
40.83 


Lbs. 
58.32 
23.74 
10.28 
14.80 


Lbs. 
24.11 
48. «1 
59.44 
64.82 


Lbs. 
15.07 
11.42 
18.81 
27.05 


Lbs. 
130.21 
155 95 
49.65 
21.08 


Lbs. 

105.32 
172.62 
50.66 
59.82 


Lbs. 

44.91 

15 63 

1.75 

4.59 


Lbs. 

18.f-4 
10.65 
9.53 
9.73 


Lbs. 

10.85 

8.88 

10.79 

12.51 



When these aiiioiiuts are expressed as parts per million 
of the dry soil in the form of nitrogen, they stand 3.38, 
1.61, 0.72 f<n- eorn; 3.87, 2.98, 1.00 for clover; 1.25 for 
alfalfa and ('».!>!» for potatoes, and yet with these small 
amonnts of nitr<)i»,en in the soil dnrinc,- the time when the 
chief i>'rowtli was being made, large yields were produced. 

118. Limits of Nitric Nitrogen at Which Corn and Oats 
Turn Yellow. — Taking samples of soil from the surface 
foot n[)on which oats were turning yellow and under adja- 
cent areas where the plants were normal green it was found 
that two sets of duplicate determinations gave 

Oats yellow Oats green. 
( June 10 .025 .213 

Parts of nitric nitrogen per million of dry .-^oil - 

(June 11 .027 .297 

Th-ese amonnts, when expressed in pounds per acre and 
•as nitrates, are only .392 lbs. and 3.813 lbs., respectively, 
for the yellow and green oats. 

Table showing the amounts of nitric nitrogen under corn rows 
where leaves are turning yelloiv and tvhere they are yet 
normal green. 



Depth. 


Plot 9. 


Marsh soil. 


RandaU field. 


Yellow. 


Green. 


Yellow. 


Green. 


Yellow. 


Green. 


1st foot 


0.61 
0.14 
0.41 
0.42 


0.92 
1.70 
2.95 

1.82 


0.95 
0.40 

0.07 
0,00 


3.62 
1.41 

0.52 
0.00 


0.10 
0.06 
0.25 
P.3C 


0.95 


2d foot 

3d foot 

4th foot 


0.60 
0.37 
0.30 







103 



Small as those amounts of nitric nitrogen are the yield 
of corn on plot 9 was a mean of 8,000 lbs. of water-free 
matter per acre. On another plot where the yield was 
11,440 lbs. of water-free matter pen* acre the nitric nitro- 
gen was reduced as low as 1.440 parts per million in the 
iirst foot and .726 parts in the second foot. 

It must be understood that in these cases the demands 
for nitrogen were so urgent that the phnits were taking it 
up almost as rapidly as it could be produced, leaving the 
amouuts so low, as the figures show. 

119. Nitrates of Fallow and Cropped Ground. — In the 

table whicli follows arc given the amounts of nitrates 
found under diiferent crops and, at the same time, under 
immediately adjacent fallow ground which had been cul- 
tivated and kept free from weeds. 



1st foot. 
2d foot. 
3d foot . 
4th foot. 

l.st foot. 
2d foot. 
3d foot . 
4th foot. 

1st foot. 
2d foot. 
3d foot . 
4th foot. 



Oats. 



Nitrates. 



5.94 
8.12 
4.73 
4.60 



Total 

salts. 

70.94 
114.6 
124.7 

39.44 



Oat,>< 



3.25 
3.22 
2.95 
2.70 



80.35 
162.1 
102.7 

58.24 



Oats. 



2.47 
2,46 
3.83 
3.16 



78.56 
102.9 
72.98 
33.99 



Fallow . 



Nitrates. 



246.40 
26.75 
6.50 

2.84 



Total 

salts. 



199.3 
123.5 
108.0 
42.10 



Fallow. 



143.05 
;;9.50 

8.87 
4.10 



206.1 
254.3 
115.0 
95.32 



Fallow . 



129.15 

35.60 

9.11 

4.08 



211.3 
254 7 
117.8 
61.92 



Barley. 



Nitrates 



2.62 
5.10 
4 04 
3.03 



Total 
salts, 

61.72 
87,08 
112.6 
51.76 



Peas. 



8.38 
18.57 
6.59 
2,66 



77.00 
197.2 
135.8 

44,62 



Spriiif,' rye. 



1.24 
2.62 
2.07 

2.78 



77,34 
102.1 
94.82 
48.85 



If the mean anionnt of nitrates in the surface foot of the 
fallow ground and uikKt the crops are expressed in pounds 
per acre they stand 4T;i.G5 to 10.88. This ditference is 
enough for 85 bushels of oats per acre, where the ratio of 
grain to straw stands as 3 to 5. 



104 



120. Loss of Nitrates from Fallow Ground During: Winter 
and Spring-. — A lidd wliicli Ims hccn kcjit fallow <liii'ii)i;' u 
wliolc season and cnll i\ alcd cil licr once per week or once? in 
two weeks had llie nitrates dcterniincMl in it on .\nL!,nst 25 
and ai^aiii tlie next spring;, .\|(i'il ."lO. Tlie Held was di- 
vided into nine plots and the nitric nitroi^cn was deter- 
niineil in each one lo a depth of fonr feet on l)(»tli dates. 
The resnils are iiiven in the next tal)le. 

liable shoiviiif/ the amount of nitric nitrofini found in faU.oiv 
ground after the leaching of winter and early spring. 
Pounds per million of dry soil. 



1st foot j 
2d foot^ 



3d foot^ 
4thfoot 



No. of plot. 



1900 ( 

lS9i) I 
1900 3 

iwm } 
iroi) s 

1900 \ 
1899 '( 



Apr. 


30 


AllK. 


22 


Apr. 


30 


All*;. 


22 


Apr. 


30 


Auk. 


2i 


Apr. 


30 


Aug. 


22 



1. 


2. 


3. 


4-. 


5. 


6. 


7. 


8. 


75.90 


58.31 


58.08 


55.22 


51.66 


51.25 


38.02 


44.34 


16.81 


13.. 58 


26.67 


26.80 


19.09 


16.82 


5.50 


24 07 


l.').Sl 


16,75 


7.97 


6.51 


13 06 


15.66 


17.33 


18.56 


4.31 


7.75 


1.81 


9.07 


5.74 


2.'i6 


1.43 


6.06 


2.46 


4.75 


4.93 


4.89 


3.94 


7.35 


6.04 


8.24 


.70 


.54 


2. 48 


.80 


0.54 


1.37 


95 


0.54 


2. 9.1 


2 37 


3.05 


2.35 


2.01 


2.36 


3.65 


5.60 


.hO 




1.04 




1.P5 


0.52 


0.26 


0.53 



9. 

48.26 
19.60 
14.85 
6.61 
6.71 
3 01 
5.08 
3.51 



It is clear from this tahle that liowe\'er lai'i;'e tlie leacli- 
inii- nia\' lia\'e hceu it was not enouiih to itre\'ent tli(i nitrates 



4TH FT 




Vi<i. 



o3.- l-'liowiiif; llu" 


(lirftTcncc ill Ilic niiiimiil n 


our feet of nillciw 


j;riHiii(l. tlH" succeed iiij;- spri 


Tops IkkI lii'cn i;l- 


nvii. 



r iiilrntes in the surt'Mc(> 
n^'. iiml tliiil upon wliicli 



105 



Ix'iiiii' liii;iicr tlic followiiiii' MiiN' 

Ix'fdI'C. 



Iinii tlicv were Aiiiiiist 22 



121. Nitrates on Fallow Ground in Spring Compared with 
That not Fallow. — ( 'ompnriiiii the mcnii niiioiint of nitric 
iiitr()i>,'('ii in iiiiic field plots hen rini;' crops in 1S1)!» with that 
of the nine fallow plots of the same year, as found in tlu; 
spriiiii' of 11M)(), I he anion Ills arc as st at CI I in I he laMc Ixdow 
and rcpi'csc ntcij i;i'aphically in l*'iii'. '■'>'■'>. 

I'able s/iowtiif/ the diffcrcncjH in the amounts of nitric nitro- 
gen after the n>inter and earfi/ spring rainn in ground kejyt 
fallow and free from iveeds the previous season and that 
bearing crops. 



Depth. 


1st foot. 


2d foot. 


3rd foot. 


4th foot. 


Fallow plots, pounds per acre of 


212.00 
25.24 


56.22 
15 08 


21.91 
10.00 


13.11 


Plots not fallow, pounds per acre 


7.24 






Ditt'oronce 


186.76 


41.14 


11 91 


5.87 







From tin's it is clear that tlie ci'o))s on tlie fallow n-romul 
start out in the spi-iuii' nnder coiidilions \( ry snpci'ior to 
those on the ficdds which had not heen fallow, thci'c hciiiju,' 
245. (j8 lbs. of nitrates more per acre in the surface four 
feet. 

122. Development of Nitrates Influenced by Depth and 
Frequency of Cultivation. WIk'ii a series of cylinders lik(^ 
those i-epi-esentcd in I^'ii;'. 5S, p. jsT, arc mulclied Ity stir- 
ring' at different depths and the stirrini;,- is repeated at dif- 
fei'cnt iiit(i'\-als the I'alc of formation of nitrates is ma- 
terially iiiodilied, as sjiowii in the talde helow : 

Difference in the amount of nitric nitrogen, after 258 days, due 
to differences indej)th and frequency of cultivation. 



Depth of cultivati'n. 


Cultivated once per week. 


Cultivated once in two weeks. 


1 inch deep 

2 inches deep 

3 inches deep 

4 inches deep 


Lbs. per acre. 
217,69 
32:i.44 
441.24 
387.96 


Lbs. per acre. 
213.29 

199,00 
401. (is 
245. ;i6 



106 

It can be seen that the nitric nitrogen has increased in 
both series to a de])th of '3-incli cultivation and it has in- 
creased witli tlie fi'ccincncv of the cultivation. 

123. Soluble Salts Affect the Movement of Soil Moisture - 

The varying strengtii of salt solutions in soil moisture mod- 
ify both the movement of moisture in the soil and its rate 
of loss from the surface. These movements are influenced 
(1) by changes in the intensity of surface tension; (2) 
by changes in the internal friction of the soil moisture or 
its viscosity; and (3) by modifications of the surface of 
the soil due to deposits of salts upon and within it, where 
evajtoratioii is taking place. 

124. Modification of Surface Tension by Soluble Salts. — 
As a general rule the surface tension of a strong soil solu- 
tion is greater than that of a weaker one, or of pure water, 
and in so far as this influence is operative it tends to in- 
crease the rate of capillary movement toward the surface 
or toward the roots of plants. 

125. Salts in Solution Lessen Rate of Evaporation. — When 
water has been brought to the surface of the soil by capil- 
larity it has yet to eva])orate and unless this takes j^lace the 
surface soil would become cai)illarily saturated with water 
and remain so. Since salts in solution increase the sur- 
face tension it will recpiirc a greater energy — a higher 
temperature — to throw the water molecules oft" into the air 
than would be required to do so from the surface of pure 
water and hence the evaporation from soil solutions rich 
in salts is sh)\ver than it is from Aveaker ones under other- 
Avise like conditions. As the salts become concentrated at 
the surface by evaporation the moisture becomes a stronger 
and stronger solution and hence the rate of evaporation be- 
comes less and less so far as it can be influenced by this 
factor, in this way. 

126. Viscosity of Soil Water Modified by Soluble Salts. — 

'J'lie internal friction of soil moisture is made greater by 



107 

the j^resence of salts in solutiuii and the more concentrated 
the soil solution is the greater is the internal friction, and 
hence the slower must he the rate of flow, and it may be that 
the much slower rate of capillary movement in a compara- 
tivelv dry soil is to a considerable extent due to this in- 
creased viscosity or internal friction. But as one effect of 
the salt in solution is to increase the surface tension, while 
the other decreases the flow by increasing the friction, the 
two influences Avork against each other, making the com- 
bined result less than it would be could either act alone. 

127. Deposits of Salts after Evaporation May Lessen Loss 
of Soil Moisture. — AVhere water rich in salts is being evap- 
orated from a soil' these salts may accumulate upon the sur- 
face and form a sort of mulch more or less effective accord- 
ing to its texture ; or they may be deposited as a crust upon, 
over and between the soil grains, which may nearly close 
the capillary pores and in this way lessen the loss of water 
by evaporation. Such a closing of the pores is likely to be 
more harmful in shutting out the air and in lessening the 
freedom of entrance of water after rains than it can render 
assistance in conserving soil moisture. 



C'irAPTKK IV. 
PHYSICAL NATURE OF SOILS. 

128. Texture of Soils.- Tlic size ni' soil ^rniiis iind the 
way tlicv iii'c i;r(iii|)c(l in cuinixisitc clnstci's foriuiiii;' ker- 
nels or ci-iiinhs has a \'cry i^i-cat iiilluciicc in (Ictcrmiiiiiig' 
the })liysi(',al])r()peTti('s ol' soils and their aiiricnltural vahic, 
and as soils vary (piitc as \\idel\- in tlic size and ;irraiii>'e- 
inent of their i>i'ains as they do in thcii' chemical composi- 
tion it is (dear that I his phase of soil prohlcnis must take at 
least e<pial rank with those considered in the last chapter. 

In all aii'i'icnltnral soils exce|)t the \-ei-y coarse and sandy 
ones Ihere is a composite ii-rannlai- sirnctnre wliicdi I'cnders 
them much more open and porous I ha n t hey con Id otluu'wise 
he, and when a soil is pnddlcMl this struclnre or texture is 
destroyed in a lai'iic measure and the separate i>rains are 
then hroUi;lit into the (dosest possihie arrangement, and. 
they hecoine nearix' or (piile iiiipei'\ious to hoth water and 
air, a|)proachinii' the condition <d hidck and ])ottci's clays. 

129. Size of Soil Grains.— When the fraiiuients (d' rock arc 
so coarse that vrvy few are smaller than .<1'1 id" an iiudi in 
diametei- we have a sand rather than a soil. .Most ])las- 
tering sands are made uj) of gi-ains I'anging from .01 up to 
.08 of an iixdi in diametei'. 

In the tahle which follows is gix-en the mechanical anal- 
yses of three types of soil : 

It will he seen from this tahle that only .S per cent, of 
either soil is nuide up of gi-ains haxing diameters so great 
that only _?.'! are recpiired to span a linear inch, while the 
heavy (day soil has nearly oneduilf of its w(dght nuule up 



109 



of c'rains so small that 2;"), 000 of tliciii iimst lie placod sido 
hy side to span a linear inch. 



Sandy Soil. 


Loess Soil. 


Heavy Clay Soil. 




Number of 






Number of 






Number of 




Diam. 


grains 


Per 


Diam 


grains 


Per 


Diam. 


prriun.s 


Per 


m. m. 


per linear 
inch. 


cent. 


m. m. 


per linear 
inch. 


cent. 


m. m. 


per linear 
inch. 


cent. 


1 to3 


23.1 


.4 


1 to3 


23.1 i 
31.7 f 


.2 


1 to 3 


23.1 


.8 


.5tol 


31.7 


3.0 


.5 to 1 


.5tol 


31.7 


1.2 


.4 


63 5 


6.9 


.4 


63.5 


.4 


.4 


63.5 


2.0 


.3 


84.7 


8.1 


.3 


81.7 


.6 


.3 


84.7 


1.6 


.16 


163.9 


3.0 


.16 


163.9 


.9 


.16 


1W.9 


.9 


.12 


211.9 


1.6 


.12 


211.9 


1.7 


.12 


211.9 


.3 


.072 


353.4 


1.2 


.072 


353.4 


2.0 


.072 


353.4 


.2 


.047 


510.1 


3.6 


.017 


540.1 


14.3 


.047 


240.1 


2.5 


.036 


704.3 


6.8 


.036 


704.3 


16.2 


.030 


704.3 


3.7 


.025 


1,020. 


14.6 


.025 


1,020. 


20.1 


.025 


1,020. 


5.6 


.015 


1,695. 


14.8 


.015 


1,695. 


5.6 


.015 


1,695. 


10.6 


.008 


3,226. 


30.7 


.008 


3,226. 


33.6 


.008 


3,226. 


24.7 


.0001 


25,000. 


4.6 


.0001 


25,000. 


2 5 


.0001 


25,000. 


48.0 



130. Number of Grains of Soil in a Cubic Inch. — If soil 
grains were pei'feet spheres like shot and in a iiiven soil 
thev wei'e all of a siniiie size it wonld he a simple matter to 




Fl<;. 34. Sliowitin 'lie ('(Ycct fif size :inil :iri-;i iiKciiiciit iiC soil >.M';uiis on 
the iKiri' spnci' :imiI upi'U llic iiic>\cinciil oC .-lir mimI walri- llii-(iii^'li a 



110 

determiue the number in a cubic inch. If a soil were made 
up entirely of the lai-gest size given in the last table, theiL 
23 would build one edge of a cube an inch on a side and 
the number in a cubic inch arranged in the manner repre- 
sented in the loAver part of Fig. 34 would be 

23=» = 23 X 23 X 23 = 12, 167. 

On the other hand, if they were all the size of the smallest 
grain in the table then the nund:)er would be 

25,000'' =15,625,000,000,000, 

or enough to form three and a third continuous lines of 
grains in contact from Boston to San Francisco. 

131. The Size of Soil Kernels.— It must be kept in mind 
that wdiile it is true that the heavy clay soils are made up 
largely of soil grains of the extremely small size considered 
in (130) these minute grains are generally bound together 
in gToups or kernels of various sizes and it is only by long 
boiling in water or thorough })estling that these can be 
broken down. The writer has found that when air-dry 
samples of the heaviest clay soils are thoroughly pestled in 
the dry condition it is difficult to reduce their texture to a 
finer degree than kernels averaging .01 to .005 m. m. in 
diameter or such that from 2,500 to 5,000 are required to 
span a linear inch ; but even this degree of closeness of 
texture is too fine to allow of proper drainage and soil ven- 
tilation and to permit roots to make their way through the 
soil with the freedom required for good crops. 

132. Specific Gravity of Soil Grains. — The specific gravity 
of soil grains, or the number of times they are heavier than 
an equal volume of water, varies somewhat, as does that of 
the minerals which compose them. As there are not many 
common minerals more than three times as heavy as 
water and not many lighter than 2.5 times as heavy, the 
specific gravity of soil grains will lie between these two 
figures and it is usually found to be near 2.65. 



Ill 



133. The Pore Space of Soils. — When the weight of a cu- 
bic foot of dry soil is known the amount of pore space or 
space not occupied by the soil grains may be computed from 
the specific gravity. Taking the weight of a cubic foot of 
water at 62.42 lbs., a cubic foot of dry soil, if there were 
no open spaces in it, should be 

2.65 X 62.42 = 165.4 lbs. 

With this value and the data given in (149) the Dore space 
of those soils may be calculated. Thus, for the surface 
foot we have 



Pore space = 



165.1 — 79 



165.4 



= 52.23 per cent. 



That is, in this soil the surface foot is more than half open 
space. The pore space for the six feet will be as given be- 
low : 





Weight of 
soil. 


Pore space." 


First foot 


Lbs. 

79.0 
92.62 
104.59 
106 21 
111.06 
111.06 


Per cent. 
52.23 


Second foot 


44.00 


Third foot 


36.76 


Fourth foot 


35.78 


Fifth foot 


32.85 


Sixth foot 


32.85 







Thus it is seen that the unoccupied space in a soil varies 
from more than half to less than one-third of its volume, 
the finest grained soils having the largest pore space and 
the sandv soils and sands the smallest. 



134. Pore Space Between Spherical Grains. — It can be 
shown mathematically that when a space is filled wdth 
spheres all of one size and these are given the closest pos- 
sible packing, having the arrangement shown in the upper 
part of Fig. 34 and Fig. 35, the pore space must be 25.95 
per cent. ; but when the spheres are given the closest possi- 
ble packing and the arrangement rejn-esented in the lower 



112 



part of Fig. o4 and in Fig. 8G, then the pore space mnst 
be as large as 47.64 per cent. In the first case the water 
capacity of such a soil with the pores entirely tilled wonld 




i'jc. J.j. Sliowiiiu llu- closi'st pacldim ijf splu-rical soil urains. the <■!»■- 
meiit of volume and tlie direction of lines of flow. Face annles (id 
ana 120°. (Aftei- Slichter.) 

be 3.114 acre-inches per acre-foot and with the second ar- 
rangement the maximnni water capacity would be 5.7108 
acre-inches i)er acre-foot. 

l^either of these arrangements would be likely to occur 
throughout a mass, and hence the 2,'eneral tendency will be 



113 



to form a }>orc space between these two extremes, and Fig". 
37 shows what the observed pore space is in soils, sand, 
crushed rock aiul ('nis1ie(l ahiss. Tt will be observed that 




1- ic. oti.— Shdwiiitc the cl.iscsl ii.-icUiim' of siilicrii-nl ^T.iiiis. the ficiiiciit 
of Yohiiue. !Ui(l the (lircctidii nf lines of flow when the face anfjlf"^ 
arc 90°, W anil 120\ (After Slicliter.) 

the finest clay soils, and indeed the finest g-rained nniterials, 
have the largest pore space. It will also be noted that the 
largest observed pore space exceeds the largest theoretical 



114 



I^ore space and that the smallest observed pore space also 
falls below the smallest theoretical limit for spherical 
grains of a single size. 




Fig. 37.— Showing the obsei'vecl pore space of different liinds of soils and 
sands and tlieir relation to the theoretical pore space of spheres of 
a simple diameter. 

135. Amount of Pore Space Determines Maximum Water 
Capacity of Soil. — The amount of water a soil may contain 
when below the level of the ground water surface is meas- 
ured by the pore space. So too in the case of heavy and 
protracted rains the pore space determines the number of 
inches of water which may enter the ground before it be- 
comes so filled that surface drainage must carry away that 
which is falling, and it will be readily understood that in 
the clay soils, where the pore space is so high, very large 



115 

amounts of Avator may be stored in them to drain away 
gradually in the underflow. 

136. Subdivision of Pore Space Determines the Rate of Per- 
colation and Drainage. — If reference is again made to Fig. 
34: it will he clear at a glance that water must flow through 
spaces filled with these different sizes of spheres at very 
different rates. Where the spheres are largest there are 
16 passage-ways for the movement of air or of water ; but in 
the middle section where the spheres have one-half the 
diameter, the number of passages is -l times as great, while 
in the last section with spheres of one-quarter the size the 
number of passages is 16 times as great. 

The aggregate area of the cross-sections of the pores is 
exactly the same in the three cases, and from this it follows 
that the areas of the cross-sections of single pores are to 
each other as 16 : 4 : 1. 

The coarse S2>heres divide the column of water into 16 
streams, the medium ones divide it into 64 streams, while 
the smallest spheres divide the column into 256 streams, 
each having only one-sixteenth the sectional area of the 
first. But to subdivide the column into 256 streams in- 
stead of 16 means that the friction must be much greater 
in the aggregate on the smaller streams, and hence that the 
flow must be slower. 

137. Method of Determining the Pore Space of Soil. — The 

simplest method of determining the pore space of soil is to 
pack the dry material into a cylindrical vessel containing 
100 c. c. until it is even full, and then weigh and compute 
the per cent, of pore space from the volume, weight and 
specific gravity, using the formula 

Vd — W 



Vd 



where Y is the volume of the vessel in c. c, d is the specific 
gravity and W is the weight of the soil in grams. 

To detennine the pore space in undisturbed field soil 



116 



the simplest method is to use a soil tube, represented in 
Fig. 38, taking a nnml)er of cores of the desired depth, 



Fii;. 38.— Showing- soil tube for taliing sami)les of soil. 

drying them, and then c<:iin})nte the pore space with the 
formnla abo\'e. 

138. Largest Possible Pore Space. — The largest possible 
])OYC Space in soils will be found in the cases where the com- 
ponnd or kernel-strnctnre is most marked. Referring 
again to Fig. 3-4, imagine each sphere there represented 
to be made njt of other very mnch smaller spheres having 
the same general arrangement. Were this the case it is 
clear that in consequence of the compound spheres the soil 
must have a pore space not less than 25.95 jDer cent, with 
one arrangement and 47.64 per cent, with the other. But 
in addition to this pore space there must be a like pore 
space within each compound sphere so that in the first case 
the total ]iore space would be 

2.^.95 + [25.95 per cent, of (100 — 25.95)] = 45.17 

and in the second case 

47.64 + [47.64 per cent, of (100 — 47.64)] = 72.58 per cent. 

The first pore space, 45.17, it will be seen, lies close 
to that possessed by the finer soils but the latter is larger 
than anything ever found except it be in the loose mulches. 

The smallest pore spaces result when grains of different 
sizes are so related that the small ones fall into the pores 
formed by the large ones without at the same time crowd- 
ing them farther apart. Eeferring again to Fig. 34, it 
will be seen that if small spheres are packed into the pores 
there shown, with the same arrangement that the large 
ones have, the original 25.95 per cent, and 47.64 per cent. 



117 



of pore space avuuKI be occupied to the extent of T-i.OS 
per cent, in the lirst case and of 52.36 per cent, in the 
second case. Such a condition would leave only about 
6.73 per cent, of pore space for the closest packing. 

Such arrangements as this are not likely of course to 
occur in nature but in the construction of macadam roads 
and in all concrete work a definite effort is made to reduce 
the pore space to the smallest possible limit by using 
crushed rock, graA'el, sand and finally cement to fill all 
pores as completely as possible. 

139. Number of Soil Grains per Unit Weight. — If soil 
grains were all spheres and in a given case they were all 
of the same size the number in a gram could be found by 
the equation 

Weight of soil 
No. of grains ^= Ttd^ >< sp. gr. 
6 

where the weight of the soil is in grams and the diameter 
of the soil grains, d, is in c. m. 

In the table below are given in round numbers the num- 
ber of grains in one gram and in one pound of soil, sup- 
posing the grains all spheres and to have a specific gravity 
of 2.65. 



Diameter. 


No. of grains in 
one gram. 


No. of grains in one lb. 


1 . m. m 


720 

720,000 

720,000,000 

720,000,000,000 

720,000,000,000,000 


326,903 




326,903,000 




326, H03, 000, 000 


.001 m. m 


326, 903, 000, 000, 000 


.0001 m. m 


326, 903, 000, 000, 000, 000 







That is to say, 720 multiplied by 10 used as a factor 3, 
6, 9 and 12 times gives the number of grains in a gram 
of soil in round numbers and the number in a pound may 
be found by using 10 as a factor in the same way and 
the number ^3 62,9 0^3 . 

If the soil were made up of some grains of all the sizes 
7 



118 

in the table, then to find the total number in a gram or 
pound it would be necessary to multiply those numbers 
by the per cent, of each size found in a gram of the soil 
and add the several products. If the soil were made up 
of 20 per cent, of each size in the table the number would 
be as follows : 



Diameter. 


Per cent. 


No. of grains per gram. 




20 
20 
20 
20 
20 


144 




144,000 




144,000,000 


.001 m. m 


144,000,000,000 


.0001 m. m 


144,000,000,000,000 


Total 


144,144,144,144,144 









140. Amount of Soil Surface Possessed by a Gram of Soil. 

■ — ]\[uch of the water retained by soils is held there in the 
form of thin films surrounding the grains and the larger 
this surface is the more water may be retained. So, too, 
the solution of plant food from the grains takes place at 
their surfaces and the larger the amount of surface the 
more rapidly the solution may take place. 

The extent of soil-surface in a gram of soil can be found 
by multi])lying the number of grains by the surface of one 
grain or by introducing Trd" into the etpuition of (139), 
thus : 

Weight X^a^ 6 X weight 



^d-* X sp. gr. d X sp. gr. 
6 



= soil surface 



expressed in square c. m. 

Using this formula to compute the surface in one gram 
of soil grains having the sizes given in the table of (139) 
the results below are obtained : 



Diameter in grains. 


Surface per gram 
sq. cm. 


Surface per pound 
sq. feet. 




22.64 

226.41 

2,264 15 

22,641.51 

226,415.14 


11.05 




110.54 


.01 m. m 


1,105.38 




11,053.81 


.0001 m. m 


110,538.16 







119 

It will be seen fruiii this table that the internal surface 
of an ideal soil increases in the same ratio that the diam- 
eter of the grains decreases, that is, reducing the diameter 
one-half doubles the surface to which water may adhere 
and upon which it may act. 

141. Difficulties in Determining the Surface of a Soil Accu- 
rately. — While it is possible to determine accurately the 
surface in a given weight of sjiheres of known dimensions 
the case is quite different with true soils. Indeed, it is 
not practicable to determine with much accuracy the sur- 
face in a soil. This will be clear from a consideration 
of a simple problem. 

Take a soil composed of grains, (a) .009 and (b) .00015 
m. m. in diameter and let these be mixed in the propor- 
tions of 

A. 90 per cent, of (a) with 10 per cent, of (b). 

B. 10 per cent, of (a) with 90 per cent, of (b). 

C. 50 per cent, of (a; with 50 per cent, of (b). 

Under these conditions the surface of one gram of such 
mixtures of soil having a specific gravity of 2.65 is 

For A. 

Surface. 

90 per cent, of grains (a") .009 m. m. diameter 2,264 sq. cm. 

10 per cent, of grains (b) .00015 m. m. diameter 15,094 sq. cm. 

Total surface 17,^58 sq. cm. 

For B. 

10 per cent, of grain.s fa") .009 m. m. diameter 251 .6 sq. cm. 

90 per cent, of grains (b) .00015 m. m. diameter 135,848.9 sq.Jcm. 

Total surface 136,100.5 sq. cm. 



For C. 

50 per cent, of grains fa) .009 m. m. diameter 1,258.0 sq. cm. 

50 per cent, of grains (b) .00015 m. m. diameter 75,481.7 .sq. cm. 

Total surface 76,739.7 sq. cm. 



120 



The iuinil)er of grains in one gram of each of these mix- 
tures woiihl be as iiiven below : 





A. 


B. 


C. 


(a) 


889, 75:-!, 061 
21,354,187,192,118 


98,861,363 
192,188,0)3,097,345 


494,306,818 


(b) 


106, 770, 833, 333, :«3 






Total 


21,353,076,945,r.9 


192,188,151,958,708 


100,771,327,640,151 



It is the custom to find the diameter of soil grains 
either by direct measurement or else by comiting and 
weighing a given nnmber of grains and then compnting the 
diameter of the mean grain from the weight and specific 
gravity. If the diameter of the mean grain in the above 
three ]>roblems is computed by each of these methods the 
results will be as below: 

If the surface of a gram of soil is computed from each 
of these diameters the results given below will be found : 



Actual surface per gram of soil 

Surface computed from the grain of meau diameter 
Surface computed from tiie grain of mean weight.. 



sq. cm. 

17, 358 

150, 570 

10,053 



sq. cm. 

136,101 
150, 939 
145, 734 



76, 740 
150,902 
119,804 



These results are very different and differ so much from 
the actual as to make them of little value in determining 
the actual surface a given soil may possess. 

It has been the practice to take as the mean diameter 
of the soil grain the average between the diameter of the 
largest grain in the group and the smallest, which in the 
above problem WM)uld give .004575 as the mean value. 

But to use this to compute the surface in a gram of soil 
would give the results below : 



Computed from 


Computed from the true diameters in true proportions. 


the mean of the two 
extreme diameters. 


A. 


B. 


C. 


4,949sq. cm. 


17,358 sq. cm. 


136, 101 sq. cm. 


76, 740 sq. cm. 



121 

Here it is seen that the computed sm'face, 4,949, is very 
far indeed from either of the true values 2,iven nnder A, 
B and C. 



142. Effective Diameter of Soil Grains. — While it is not 
possible to deteniiiiK' cither the mean diameter of the 
grains in an ordinai-y soil or the amount of surface a given 
weight of soil may possess with even approximate accu- 
racy, it is possible for the simple sands, at least, to deter- 
mine the diameter of a fjraiii which, if substituted for the 
actual ones, would ])eruiit, under like conditions, the same 
amount of air or of water to flow through. 

The method is based upon the laws of flow of fluids 
through capillary tubes and aims to compute from the ob- 
served rate of flow of air through a given column of soil 
the effective diameter of the capillary pores and from this 
the size of spherical grains which would be required to 
form such capillary tubes as those computed. The theory 
of the method is fully set forth in Prof. C. S. Slichter's 
paper. ^ 

143. Description of the Method. — The apparatus used to 
determine the effective size of soil grains is represented in 
Fig. 39, and consists of a cylinder in which a sample 
of soil is carefully packed and weighed to determine 
the per cent, of pore space. When this has been done 
the tube is connected with the aspirator and the rate at 
which air will flow through it under a measured tempera- 
ture and pressure found. When these data have been ob- 
tained, then the formula below, used with the table given, 
enables the effective diameter to be computed when the 
flow has been measure<l at the temperature of 20'^ C. 



1 Nineteenth Annual Report of the U. S. Geol. Survey, Part II. 



122 



d^ =k 



h 
spt 



[8.9434 — 10] 



where 

d = diameter of grain in c. m. 

h = length of sand column in c. m. 

s = area of cross-section of sand column in sq. c. ra. 

p = pressure in c. m. of water at 20° C. 

t = time in sec. for 5,000 c. c. of air to flow through at a tem- 
perature of 20° C. 
[8.9434 — 10] is a logarithm of a constant 
k is a constant taken from the following table. 




Fig. 39.— Showing aspirator for determining the mean effective diameter 
of soil grains. A. aspirator l>ell; B, pressure gauge; C. air meter; 
D, aspirator tube for samples. 



Per cent, of pore 
space. 


Log. k. 


d. 


Per cent, of pore 
space. 


Log. k. 


d. 


26 


1.9258 
1.8695 
1 8195 
1.7701 
1.7199 
1.6732 
1.6277 
i..W47 
1.5409 
1.4999 
1.4592 


563 
500 
490 
502 
467 
455 
430 
438 
410 
407 
400 


37 


1.4193 
1.3816 
1.3445 
1.3078 
1.2725 
1.2374 
1.2024 
1.1690 
1.137C 
1.1058 
1.0729 


377 


27 


38 


371 


28 


39 


367 


29 


40 


353 


30 


41 


351 


31 


42 


345 


32 


43 


339 


33 


44 


320 


34 


45 


312 


85 . .. 


46 


329 


36 


47 











144. Observed Flow of Water Through Sand Compared 
With That Computed From the Effective Diameter. — The ac- 
curacy of the method described in (143) is Lest sliown by 
computing- from the effective diameter of the soil grains 
what the flow of water ought to be and then measuring the 
flow of water to see how it corresponds. This has been 
done and the results are given in the table below : 



Grade of sand. 


Effective 

diameter of 

grain. 


Computed 
flow of water. 


Observed 
flow of water. 


8 


m. m. 

2.54 
1.808 
1.451 
1.217 
1.095 
.9149 
.7988 
.7146 
.6006 
.5169 


Gms. 

2,277 
1,132 

757 

522 

453 2 

297.5 

193 

122 
80.6 
66.8 


Gms. 
2,298 


7 

6 


1,080 
756 


hVt 


542 


5 


604.6 


4 


3i9.2 


3 


210.0 


2 


138.6 


1 


94.8 





72.3 







When it is observed that the effective diameter of the 
grains in these sands was found by measuring the flow of 
air through one sample in one piece of apparatus and the 
flow of water was measured through another sample and 
in another piece of apparatus, and that the flow varies as 
the squares of the diameters of the soil grains, it is clear 
that the effective diameter has a very exact value so far as 
the flow of fluids is concerned. 



124 

145. The Effective Diameters of Soil Grains and the 
Amount of Surface Computed From Them. — We have no 
means of knowing vet how accnrately the conijnited sur- 
face of soil grains in a given weight of sample compares 
with that which is possessed by it. We do know, however, 
that the comparison is accurate enough to furnish a valua- 
ble basis for comparing different types of soils, and in the 
table which follows is given the effective diameters of sev- 
eral kinds of soils, together with the pore space and the 
computed amount of soil surface per cubic foot of dry soil. 

Table of computrd surface of soil grains in different types 

of soil. 



Kind of soil. 



Finest clay soil. .. . 

Fine clay soil 

Fine clay soil 

Heavy red clay soil 
Loamy clay soil .. . 

Clayey loam 

Loam 

Loam 

Sandy loam 

Sandy soil 

Sandy soil 

Coarse sandy soil. , 



Effective 
diameter of 
soil grains. 



m. m. 

.004956 

.007657 

.008612 

.01111 

.02542 

.01810 

.02197 

.02619 

.03035 

.07555 

.1119 

.1432 



Per cent. 

of 
pore space. 



52.94 
45.69 
48.00 
44.15 
49.19 
47.10 
44.15 
34.49 
38.83 
34.45 
3i!.49 
34.91 



Surface of soil 

grains in 
one cubic foot. 



Sq. Ft. 

173,700 
129, 100 
110,500 
91,960 
70,500 
53, 490 
46,510 
45, 760 
36,880 
15,870 
11,030 
8,S18 



It Avill be seen from this table that the amount of surface 
in the true soils is indeed very great, ranging from a little 
less than a quarter to more than a third of an acre in the 
sandy soils, through more than an acre in the loams to as 
much as four acres per cubic foot in the finest clay soils. 
The amount of soil surface in the upper four feet of every 
cultivated field ranges from not less than one acre to more 
than Ifi acres per each square foot of surface cultivated. 



146. Relation of the Surface of Soil Grains to the Water 
Capacity. — A large portion of the water held by a soil is 
spread out as a thin film surrounding the soil grains and it 



125 

is generally true that the larger the surface; of the; soil 
grains the more water the soil will retain. 

If a marble is lifted ont of Avater it retains a film sur- 
rounding it and its surface is wet; so if rains fall upon a 
sand or soil surface until percolation takes ])lace. there is 
held back upon the grains a certain amount of water which 
is characteristic of or peculiar to each type. It is clear 
that a soil whose internal surface is 4 acres per cubic foot 
may contain a large amount of water even though the film 
is extremely thin. In an acre there are 43,560 sq. ft. and 
in four acres 174,240 sq. ft. The thickness of a water 
film on this surface sufficient to equal 4 inches on the level 
per square foot of soil would be 

A 1 

of an inch 



174,210 " 43,560 

or one-half the thickness of the film of a soap bubl)le when 
it becomes yellow just before appearing black and breaking, 
from thinning ont. This thickness is also about ^ the di- 
ameter of the soil grain itself. 

In the case of a fine sand having grains .08188 m. m., 
which retains, after complete drainage 8 feet above stand- 
ing water, 3.44 per cent, of water, the film would have to 
have a thickness of only about gV of the diameter of the 
grain, and when containing 20 per cent, of its dry weight 
then the film need have a thickness of only about tt of the 
diameter of the sand grains, that is, .0072 m. m. 

It is clear, therefore, from these considerations that the 
surface of soil grains has much to do in determining the 
water-holding power of a soil and that the films may be 
very thin and yet on account of their great extent represent 
a high per cent, of the soil itself. 

147. Movement of Air Through Soil. — There is perhaps 
nothing which shows how physically difl:"erent the fine and 
the coarse grained soils are as clearly as the rates at which 
air will pass through them when dry, and in the next table 
some of these are aiven. 



126 



It will be seen from this table that when the grains are 
so large that 10 of them will s])an a linear inch only 37 
seconds are required for a jn-essiire of .1 foot of water to 
force 5,000 e. e., 5.3 (pnirts, of air throngh a cohmin a foot 
long and .01 of a scinare foot in cross section; but in the 
finest clay soil, Avliich makes the best grass land, where 
5,125 grains must be set in line to measure a linear inch, 
then the time reijuired is 2,983,000 seconds for tlic same 
amonnt of air uiuler the same conditions to be forced 
throngh, a ratio of 37 seconds to 45 days. 



Table shotoing the differences in the rate of movement of air 
through gravel, sand and i<oils of different types wlien the 
columns are 1 foot long, .01 ft. in cross section and under a 
pressure of .1 ft. of water. 



Description of material. 



Fine gravel, srade No. 8.. 
Fine gravel, grade No. 7.. 
Fine gravel, grade No. 6.. 
Fine gravel, grade No. 5.5 
Coarse sand, grade No. 5. 
Coarse sand, grade No. 4. 
Coar.so sand, gradn No. 3. 
Coarse sand, grade No. 2. 
Medium sand, grade No. 1 
Modinni san<i, giade No. 
Fine sand, grade No 00 .. 
Fine sand, grade No. 100 . 

Coarse sandy soil 

Sandy soil 

Sandy soil 

Sandy loam 

Coarse loam 

Loam 

Clayey loam 

Loamy clay 

Heavy red clay .soil 

Clay soil 

Fine clay soil 

Finest clay soil 



No. of grains 

per 
linear inch. 



10. 

14.0 

17.5 

20.6 

24.3 

27.8 

31.8 

35.5 

42.3 

49 1 

143 

310 

177 

227 

336 

837 

970 

1.56 

403 

647 

286.0 

949.0 

310.0 

125.0 



Per cent. 

of 
pore space. 



37.60 
38.44 

38.85 
39.26 
39.88 

:w.53 
36.26 
34.66 
34.43 
34.42 
34.20 
35.32 
34.91 
32.49 
34.45 
38.83 
34.49 
44.15 
47 10 
40.19 
44.15 
48.00 
45,96 
52.94 



No. of seconds 

for 5,0(X) c. c. 

of air to flow 

through . 



37 
67 
99 
138 
184 
260 
416 

ei?. 

869 

1,178 

10,370 

44,310 

14,580 

30, 460 

54,910 

227,400 

45, 750 

2j2,200 

476,600 

804,600 

1,129,000 

1,412,000 

2,057,000 

2,933,000 



It should be understood that this slow rate of movement 
of air through the finest clay soils Avas observed when the 
air-dry soil had been pulverized in a mortar and made as 
fine as practicable before jiacking into the aspirator. Un- 



127 



der field conditions, as lias hcon poiiitcil out, a good clay 
soil lias its clusters of various sizes and there are passage- 
ways of various sizes and forms which allow both air and 
water to move much more freely than has been recorded 
in the table and if it were not so j^lants could not thrive 
in them. 



148. Permeability to Air of Undisturbed Field Soils. — The 

rate at which air msij flow 
through soils in their natural 
condition, in place in the field, 
may be readily studied with an 
apparatus such as is shown in 
Fig. 40. When the soil tube 
A is driven into the ground to 
near the depth at which the 
flow of air is to be measured it 
is recovered, the core of soil re- 
moved and the tube returned to 
its place, when the aspirator is 
connected as shown in the cut, 
and the time required for a 
given volume of air to be drawn Fig. 40 showing apparatus for 

tliroiioli (If'ff-'vniinPfl Tn tbp^P measuring tlic porineability to 
TUlOUgn (UTCimineu. in luese airot soils in tlie field. Acoreof 

field studies it will be found soil is removed to the desired 

depth and the soil tube replaced. 

that the dryer the soils arc the 

more freely air passes through them l)ut that wlien they 
are saturated with water, as just after heavy rains, little 
or no air will i)ass through them even under a pressure of 
12 inches of water. 




149. Weight of a Cubic Foot of Dry Soil. — A cubic foot of 
undisturbed air-dry soil varices in weight between quite 
wide limits, the humus soils being the lightest, and the 
coarse sandy soils the heaviest. The writer has found a dry 
soil to have the weight jx'r cubic foot given in the ta1)le be- 
low : 



128 



Pounds per cubic foot 
Pounds per acre 



1st foot. 



79 
2,740,000 



2d foot. 



92.62 
4,034,000 



3d foot. 



104.59 
4,557,000 



4th foot. 



106.21 
4,637,0C0 



5th foot. 



111.06 

4,810,000 



6th foot. 



111.06 

4,840,000 



Slnibler gives the ^veigiit of a enl)ie foot of dry soil as 
follows : ; 

Dry calareous or siliceous sand 110 lbs. 

Half .sand and half clay 96 lbs. 

Common arable soil 80 to 90 lbs. 

Heavy clay 75 lbs. 

Garden mould rich in vegetable matter 70 lbs. 

Peat soil 30 to 50 lbs. 

As a number easy to remembei' it may be taken as a 
safe fig-ni'e that the mean weight of the surface fonr feet 
of field soils is, in ronnd nnmbers, 4.000,000 lbs. per acre- 
f.:.ot. 



150. Heavy and Light Soils. — These terms are used more 
with reference to the ease with which soils may be worked 
than to their weight per cnl)ic fodt. A soil that is nat- 
urally mellow and easily stirred i.s called a light soil, 
while one that becomes hard when dry and which tends to 
form clods is often called heavy. Sandy soils, as shown in 
(149) are among the heaviest we have while the clayey va- 
rieties are the lightest by weight except the'hnmns types. 
The prairie loams which contain mncli Inimns and the 
black swamp soils when drained are among the most mellow 
of all soils, the large amonnt of hnums preventing the soil 
grains from adhering and baking. 



120 



CHAPTER V. 
SOIL MOISTURE. 

151. Occurrence of Moisture in the Soil. — For purposes of 
discussing the cuhiiral rehitions of soil moisture water may 
be said to occur in the soil under three conditions : 

(1) That which tills the pore spaces between the soil 
grains and is free to move under gravitational or hydro- 
static pressure and may be called gravitational or hydro- 
static irate r. 

(2) That which adheres to the surfaces of soil grains 
and to the roots of plants in tilms thick enough to allow 
surface tension to move it slowly from place to place, and 
which may be called capillary water, 

(3) That still retained on the surfaces of soil grains 
when they become air-dry ; whose chief movements are 
those of evaporation and condensation and which has been 
designated Jtygru.scopir viaistare. 

152. Gravitational Water. — AVhen Avater in a soil in- 
creases in quantity suificiently to move readily under the 
pull of gravity it may be harmful in three ways: (1) by 
washing out the soluble plant foods, thus leaving the soil 
poor ; (2) by excluding the air and thus causing suffocation 
of the roots of plants and micro-organisms living in the 
soil; (3) by preventing surface tension and by dissolving 
cementing materials, thus destroying or reducing the gran- 
ulation of soils, injuring their texture. It may be helpful 
in two ways: (1) by replenishing the capillary moisture 
when this has become too small to enable crops to supply 
themselves, and (2) by washing out and carrying away sol- 
uble substances which, if allowed to accumulate, become in- 



130 

jurions, such as black alkalies and possibly toxic principles 
developed bv the roots of plants or soil organisms or dnring 
their decay. 

153. Capillary Water. — It is in this condition or quantity 
in the soil from which crops and soil organisms chiefly de- 
rive their supply of water, and the right amount at all 
times is therefore very inqwrtant. It is in the capillary 
water, too, that most of the plant foods derived from the 
soil are held in solution and with it moved to the plants as 
needed. When the texture of the soil is right the capillary 
water simply surrounds the soil grains and soil granules 
as a thin sheet which is continuous where the grains are 
nearly or quite in contact, but there are always open spaces 
through Avhich the air may circulate and supply the needs 
of roots and soil bacteria. 

If the soil is puddled and the granules broken down then 
the surface films on the smaller soil grains come so nearly 
in complete contact that there is insufhcient room for air 
to diffuse and plants cannot thrive in it. 

154. Hygroscopic Water. — :\roisture in this form possibly 
plays an important part in the actual solution of plant food 
from the soil and fertilizer grains because it is this portion 
which lies in immediate contact where the action must take 
place ; but if this is true it can only do its work rapidly 
when capillary water is also present to carry away from 
the dissolving surfaces the products which are being 
formed. 

Polished surfaces do not as readily rust as those which 
have become tarnished or otherwise i^Dughened. When a 
steel knife blade has become a little rusty the rusting then 
goes on much more rapidly, possibly because each particle 
of rust becomes invested with its film of hygroscopic mois- 
ture, and when these lie against the fresh metal the water 
can have a greater thickness and permit a more rapid move- 
ment of the compounds formed, away from the corroding 
surface. 



131 



It is not j)n»baljlo, however, that the hygroscopic mois- 
ture of a soil can in an}- direct way aid plant growth. 

155. Ways of Expressing the Water Content of Soils. — The 
amount of Avater a soil will or may contain has been ex- 
pressed in different ways : ( 1 ) As a per cent, of the Avet 
weight of the soil, (2) as a per cent, of the dry weight of 
the soil, (3) as a per cent, of the volnme of the soil, (4) 
in pounds per cubic foot, (5) in inches per cubic foot. The 
aiiinnnt of moisture 9, soil does contain may be most readily 
and precisely stated as per cents, of the wet or dry weight, 
but for agricultural purposes it is best to state the amount 
in per cent, of the volume or in inches per cubic foot. 

156. The Maximum Water Capacity of Soils. — The lai-o-est 
amount of water a soil may contain is expressed by its per 
cent, of pore space and if reference is made to the table in 
( 145 ) it will be seen that this ranges from about 32 to more 
than 52 per cent., that is from 4 to 6 acre-inches per acre- 
foot of soil, and from 20 to 32 lbs. per cubic foot. These 
amounts of water, however, are never found in soils under 
field conditions. 



157. Water Capacity of Soils Under Field Conditions. — 

The amount of water which may be retained by soils under 
field conditions is extremely variable and depends upon a 
number of factors. In the table below are given the 
amounts of water which were found in three types of soil 
with the undisturbed field texture-', w-hen they contained as 
much as they would retain after a few days of drainage fol- 
loM'ine' lieavv rains. 



Capacity of field soils for moisture. 



Depth . 


Sandy Joam. 


Clay loam. 


Humus soil. 


First foot 


Per cent. 

17.65 
14.59 
10.67 


Per cent. 

22.67 
19.78 
18.16 


Per cent. 
44.72 


Second foot 


31 H 


Third foot 


21.29 







.'^•7 



In this table the third foot in each case is more or less 
saiidv and for this reason shows jiercentagely less water 
than the soil above. It Avill be seen that the surface foot 
of sandy loam contains the smallest per cent, of water and 
the lininns soil ilic lari>est, bnt on account of the differences 
in dry weiglit of these soils their water contents are more 
nearly e(|ual than they ajvpear, the sandy loam containing 
about Hi His., the chiv l(tam IS lbs. and the liuiiius soil 
2(> ll)s. |)(M' cnl)ic f(H(t. Kx])rcss('d in inches the amounts 
stand .■), .')..") and ."> inches nearly. 

158. Maximum Capacity of Undisturbed Field Soil. — In 

the table below are given the amounts of water wjiich com- 
pletely tilled the first five feet of undisturbed field soil, as 
determined by driving 6-inch metal cylinders one foot long 
into the soil and, recovering them, covering the bottoms 
with pcM-forated covers and then placing the cylinders nn- 
<ler water until the pores became completely filled. 



Table shoivlng ma.vimum capacitij of undisturbed field soil 

for water. 



Kind of soil. 


Deptli . 


Per cent. 
of water. 


Inches of 
water. 




1st foot 


41.3 

28 1 
28.4 
24.8 
17.4 


5 88 


Kcddisli clav 


2d foot 


5.03 


Koddisliclay 


3d foot 


5.07 


Clav with saud 


4th foot 

5tli foot 


4.67 


Very line sand 


3.76 


Total 




24.41 











In this case it is seen that two feet out of five feet of the 
soil was open s])ace which could be occu|)ied with water. 

159. Maximum Capillary Capacity of Soils for Water. — 

The amount of ^^•ater which may be retained in soils by 
capillarity is greatly influenced by the distance of the soil 
above standing water in the ground and by the fretpiency 
and amount of rainfall. The cvlinders of soil referred to 



133 



in (158) Avlicii thoroughly dried aiul then jdacod in one 
inch of water in a chamber where no evaporation conld 
take place, took np and retained hy eapilhirity the follow- 
ing amounts of water: 

Table shoiving the maximum capillari/ (■apacity for water of 
field soils with the surface 11 inches above standing water. 





Per cent, 
of water. 


Lbs. of 

water per 
cu. ft. 


Inches of 
water. 


Surface foot of clav loam contained 


32.2 
23,8 
24.5 
22.6 
17.5 


23.9 
L'2.2 

22 7 
22.1 
19,6 


4.59 
4.26 
4.37 

4.25 
3.77 


Second foot of reddish clav contained 


Third foot of reddish clay contained 

Fourtli foot of clay and sand contained 

Fifth foot of fine sand contained 




Total 




110.5 


21.24 





r^ 




A 



iitii 



Hh 



i^ 



s 



LSL 



n h 




.n 



Fig. 41.— Apparatus fm- nicasnrinfr the capilhu-y capacity of lonj,' cohinins 

of sand. 

It is clear from tliis tal)le and the last that much of the 
pore space in the clayey soils cannot be maintained full of 
water by capillarity even when the snrface is only 11 inches 
above standing water. 



13 i 



160. Influence of Distance Above Standing Water on the 
Water Capacity of Soils. — AMion the distance to the ground- 
water is considerahle the force of surface tension is not 
great enough to maintain as much water in the soil as when 
the distance is less, and the table which follows shows how 
the amount of water retained varies with the distance. The 
sands and soils were placed in an apparatus represented in 
Fig. 41, arranged so as to permit free percolation hut allow- 
ing very little evaporation from the surface. The sand 
columns were 8 feet long and percolation was allowed to 
continue nearly 2.5 years. The soil columns were 7 feet 
long and percolation from them was continued during 60 
days, at the end of which time the tubes were cut into short 
sections and the amount of water still retained determined 
by drying. 

Percentage distribution of water left in columns of sand, sandy 
loam and cJaij loain after percolation had continved tivo 
and one-half years with the sand and 60 days ivith the soils. 



Height of section above 
ground water. 


Sand 
No. 20. 


Sand 
No. 40. 


Sand 
No. 60. 


Sand 
No. 80. 


Sand 
No. 100. 


Sandy 
loam. 


Clay 
loam. 


Inches. 
96-93 


Pr. ct. 

0.27 

.22 

.23 

.22 

.23 

.29 

.44 

.89 

1.18 

1.48 

1.71 

1.80 

1.83 

1.93 

1.98 

2.02 

2.03 

2.02 

2.06 

2.17 

2.31 

2.36 

2.63 

2.86 

3.42 

4.26 

6.41 

9.77 

16.08 

19.33 

20 96 

21.58 


. ct. 

0.17 

.17 

.16 

.15 

.18 

.19 

.26 

.58 

1.16 

1.45 

1.67 

1.80 

1.86 

1 87 
1.98 
1.92 
2.12 
2.07 
2.18 
2.29 

2 48 
2.65 
3.14 
3.63 
4.71 
6.76 
9.38 

14.66 
21.31 
22.39 
23.52 
24.61 


Fr. ct. 

0.22 

.23 

.29 

.32 

.61 

1 07 

1.33 

1.57 

1.80 

1.85 

2.03 

2.18 

2.26 

2.27 

2.30 

3.38 

2.46 

2.71 

3.08 

3.46 

4.10 

5.09 

6.36 

8.74 

13.52 

23.57 

27.93 

23.61 

22.46 

22.76 

22.88 

23.54 


Pr. ct. 

1.26 

1.16 

1.34 

1 61 

1.98 

2.32 

2.61 

2.90 

3.12 

3.36 

3.56 

3.92 

4.22 

4.53 

4.88 

5.42 

6.03 

6.99 

7.47 

8.71 

10.54 

11.77 

12.95 

15.05 

17.24 

19.08 

19.37 

21.44 

22.69 

23.20 

24.22 

25 07 


Pr. ct. 

3.44 
3.44 

3.82 

3.83 

3.93 

4.19 

4.38 

4.92 

4.94 

5.70 

5.91 

6.43 

6.77 

7.72 

8.59 

9.42 

10.50 

11.34 

12.58 

13 00 

14.95 

15.90 

17.20 

17.96 

18 92 

20.49 

21.34 

21.63 

22.68 

23.39 

30.28 

24.08 


Pr. ct. 


Pr. ct. 


93-90 






90-87 






87-84 






84-81 


16.16 


21.16 


81-78 




7g-75 


16.08 


30.70 


75-72 




72-69 


16.55 


31 05 


69-66 




66 63 


16.97 


31.11 


63-60 




60-57 


17.59 


31.21 


57 54 




54-51 

51 48 


17.99 


31.94 


48-45 


18.70 


31.99 


45.42 




42 39 


19.44 


32.18 


39 36 




36 33 


20.90 


32.45 


33 30 




30 27 


21.71 


33.31 


27 24 




24 21 


21.46 


34.40 


21 18 




18-15 


22.17 


35.54 


15 12 




12-9 


22.68 


35.97 


9 6 




6 3 


27.69 


37.19 


3-0 











135 



Tliis table shows very clearly that the amount of water 
a soil can retain by capillarity is very materially iniiuenced 
by the distance it is above the zone of complete saturation 
or of standing water in the ground. The decrease of water 
upward is most rapid* in the coarsest sand and it is least 
rapid in the finest soil. 

It is remarkable that in sands so coarse as those used 
water should continue to drain away during more than two 
3'ears from so short a vertical column and that so small an 
amount of water Avas retained in the upper sections of the 
columns. It is not probable that drainage had become 
complete from the two soils although it may possibly have 
been, as there was no percolation during the last five days 
of the trial. '^ 



161. Proportion of Soil-Water Available to Crops. — JS^ot all 

the water which soils will retain is available to plants. A 
certain amount must be left overspreading the soil grains 
which the roots of plants are unable to use. The amount 
found in one field soil, when corn and clover ceased to grow 
and when the leaves curled early in the day, is given in the 
table below. In the same table is also given the moisture 
of adjacent fallow ground determined at the same time and 
which contains the least amount of water which, for this 
soil, will permit maximum croj^s. 

Soil moisture relations when growth is brought to a standstill. 



Depth of sample. 



0-fi inch clay loam .... 

6-12 inch clay loam . . . 
12-18 incli reddish clay 
18-24 inch reddish clay 
24-30 inch sandy clay. . 
40-43 inch sand 



Clover. 


Maize. 


Fallow 
ground. 


Per cent. 


Per cent. 


Per cent. 


8.39 


6 97 


16.28 


8.48 


7.8 


17.74 


12.42 


11.6 


19.88 


13.27 


11.98 


19.84 


13.52 


10.84 


18.56 


9.53 


4.17 


15.9 



The moisture containecl in tlie fallow ground shows how 
much this type of soil may retain, against evaporation and 
percolation, during a dry season, and it happens to stand 



136 



just at the Tinder limit for most vig-oroiis gTowth while the 
upper limit is given in the next tahle. 

Showing upper and loiver limits of best amount of soil moist- 
ure for one type of soil. 



Kind and depth of soil. 



Lower limit 

of soil 

moisture. 



Upper limit 

of soil 

moisture. 



Available 

soil 
moisture. 



Clay loam, first foot 

Reddish clay, second foot. 

Sandy clay, third foot 

Sand, fourth foot 



Total. 



Per cent. 

17.01 

19.86 
18.55 
15.9 



Per cent. 

25.77 
24 3 
24.03 
22.29 



Lbs. per 

cu. ft. 

6.92 

4.112 

5 722 
6.786 



23.54 



It will 1)0 seen from this table that, to In-iiig the surface 
four feet of soil from the lower limit of the best productive 
stage of water content to the upper limit, requires an ap- 
plication of 23.55 pounds per square foot, or a depth of 
rainfall equal to 4.527 inches. This therefore represents 
the available moisture in this type of soil and is about one- 
third of its full capillary capacity. 

162. Kinds of Soil Which Yield Their Moisture to Crops 
Most Completely. — When the roots of plants come to draw 
upon the supply of soil-water those soils yield their mois- 
ture to the plant most completely whose grains have the 
largest diameter or, more precisely, which have the smallest 
internal surface to which the moisture may adhere and over 
Avhicli it is spread. 

lleferring to the table in ( 161 ), giving the per cents, of 
moisture which were too low to jx'rmit the plants to supply 
their needs, it will be seen that under the corn the water in 
the sand had been drawn down to about 1 per cent. ; in the 
surface loam to 7 and 8 per cent. ; while in the intervening 
more clayey portion only to 11 and 12 per cent. The fun- 
damental truth which should be grasped here is that all 
these soils are equally dry so far as the needs of the corn 
crop are concerned, and one of the reasons why they are 



137 

so is because the thickness of tlie water lihii surrounding 
the grains is nearly the same in all the cases. 

The truth of this statement will be evident if we com- 
pute the per cent, of moisture in a soil which a given thick- 
ness of film surrounding the grains will ])roduce. 

163. Relation of Thickness of Moisture Films to Per Cent, 
of Soil Moisture. — If the data in the table of (145) is used 
the per cent, of soil moisture a given thickness of film will 
jiroduce may be com])ute(l from the formula 

Q 

where P = the per cent, of moisture in the soil. 

K = a constant, Log. 7.939845 = .0000008647 
S = surface of soil per cu. ft. taken from ( 14-5) 
Q = per cent, of dry soil obtained by subtracting the pore 
space in (143) from 100. 

Using this formula and the data in (145) it will be 
found that the per cents, of moisture stand as given below: 

With tliickness of film TolfftTJo inch the percent, of water 
will be, in the 

Heavy red clay 14 . 24 per cent . 

Loamy clay 12 . 00 per cent . 

Loamy clay 8 . 74 per cent . 

Loam 7.20 per cent. 

Sandy loam 5.21 per cent. 

Sandy soil 2 . 09 per cent . 

Sandy soil 1.41 per cent . 

Coarse sandy soil 1 . 11 per cent . 



From this table it will be seen that the coarse sandy soil 
contains only 1.1 i)er cent, of its dry w^eight of moisture 
when the heavy red clay contains 14 per cent, with the same 
thickness of film surrounding the soil grains. 

(,V)m]>aring these per cents, of moisture with th<jse con- 
tained in the soil in which the corn wilted, it will be seen 
that the sand of that soil was really the wettest soil there, so 
far as the available moisture is concerned, there being at 



138 

least -2 per ct'iit. (if moist lire vet avaihiMc. 'I'lu' loamy 
clav of (145), and liivcii in the table, has alxmt the same 
texture as that of the reddish clay in the table of (161) and 
it will be seen that its jier cent, of moisture under the corn 
M'as also about the same as that comput(\l. 

164. Available Soil-Moisture Affected by Jointed Structure 
in Clay Subsoils. — Hie tendency of clay subsoils to shrink 
and become dividi^l into small cidie-like blocks greatly di- 
mnishes the available moisture in them. This shrinkage 
not only often results in breaking rootlets in two but when 
new rootlets form they advance most rc^idily through the 
fissure planes and an> not able to place themselves in the 
most favorable relations with the soil to permit, cai)illarity 
to bring the moisture to the rootlets. It is because the 
sandy soils and loams seldom d(n'elo]> the structure referred 
to and because the rootlets and i"oot hairs are- able to secure 
a more uniform distribniion llii'onglioiU them as well as 
because of the larger size of their grains that ])lants are able 
to drain their moisture down to so low a ]Kn" cent. 

165. Available Soil-Moisture Increased by Open Structure. 

— When soils ar(^ in any way left with a loose opim struc- 
ture, as happens with dee|) ])lowing and especially with 
good subsoiling, not only is the ability of the loos(^ soil to 
retain moisture increased but a largi'r proportion of this 
retained Avater bcH'onu's available to the croj). A larger 
amount of water is retained because when jierfect cajiillary 
connection with the unstirred soil below, is broken, surface 
tension o]>})oses rather than aids gravity in ])roducing per- 
colation and s])aces too large to remain full of watt'r other- 
wise are able to retain it. 

When the soil is open and loose the case is cpiite ditferent 
from that resulting from shrinkage referred to in (164)^ 
for in this case the roots and root hairs are better able to 
enter the sejiarated portions and, as the moisture films are 
thickei", th(^ moisture is mori' readilv i2,athered. 



139 



166. Drainage May Increase the Available Soil-Moisture — 

When tlie siihsuil is too closo and too fully saturated with 
water to permit the roots of crops to penetrate it, as is the 
case where drainage is needed, the roots of })hiiits are forced 
to develop in so limited an amount of soil that wlieu a dry- 
ing time comes, and when the deiuands of the crops for 
moisture are large because of rapid growth, capillarity 
from below is not able to supply the moisture as fast as 
needed, and the result is the zone of soil occupied by the 
roots becomes so dry that growth is impeded. 

On the other hand, whei-e a field is well drained the roots 
are extended through much larger volumes of soil ; the lo- 
cal demands are thus less urgent aud tlie water need not 
move so far by capillarity before the ])laiit comes in pos- 
session of it. Under these conditions the moisture of the 
surface four feet of soil is in close reach of the roots aud 
capillarity may still add to this supply from below. 

167. The Amount of Water Required by Crops.— It has 
been determined by careful aud extended observations in 
this country and in Europe that almost any one of the cul- 
tivated crops withdraws from :'>00 to ."iOO tons of water from 
the soil for each ton of dry matter produced. Tn Wiscon- 
sin the amounts of water lost from the soil by evaporation 
during the growing season and through the jdant are given 
in the table lielow : 

Table showing the mean amount of water used hy various 
■plants in Wisconsin in producing a ton of dry matter. 





No. of 
trials. 


Water 

used per 

ton of dr.v 

matter. 


Water 
used. 


Dry matter 
per acre. 


Acre-in. of 

water per 

ton of dry 

matter. 


Barley 

Oats 


5 
20 
52 
46 

1 
14 


Tons. 

464.1 
503.9 
270.9 
576.6 
477. 2 
385.1 


luches. 

20 69 
39 53 
15.76 
22.34 
16.89 
23.78 


Tons. 

5.05 

8.89 

6.59 

4.39 

4 009 

6.995 


4.096 
4 447 


Maize 


2 391 


Clover 


5 089 


Peas 


4 212 


Potatoes 


3 3l»9 








138 


Av. 446.3 


23, 165 


5.987 


3.939 



140 



From this table it is seen that the amount of water used 
ranges from 270 tons of water with corn to 570 tons with 
clover per ton of dry matter; or Avhen expressed in acre- 
inches from 2.4 to 5.1 inches nearly, the average for the 
six crops being neai'ly 450 tons or 4 acre-inches per ton of 
drv mattei-. 

When the yields jier acre ai'c 2, ;> and 4 tons the nnm- 
bi'i's gi\'eii al)o\'e must be mult i|ili('(l l)y the same fa(;tors. 

168. Amounts of Water Required for Different Yields of 
Wheat. — 111 order to express the data of the last section in 
terms which it is more ciistoinarv to use, there is given in 
the next table the amount of water recpiired by a crop of 
wheat when the yields ])er acre range from 15 to 40 bnshels. 

Observations made by Ilellriegel in Germany show that 
wheat uses about 453 tons or 3. 998 acre-inches of water 
for a ton of dry matter. TTsing this ratio and one pound 
of grain to 1.5 ])ounds of straw the water i-ccjuired will 
stand as below : 

Table sliowincj the leant amount of water required to produce 
different yields of wheat per acre when the ratio of grain 
to straw is t to 1.5. 



Yield per acre. 




Number of bushels. 


Weight of 
grain. 


Weight of 
straw. 


Total weight 


Water used. 


15 


Tons. 

.45 
.60 
.73 
.90 
1.05 
1.20 


Tons. 

.675 
90 
1.125 
1.350 
1.575 
1.800 


Tons. 

1.125 
1.500 
1.875 
2.'<J50 
2.625 
3. 


Acre-inch. 

4.498 


20 


5.998 


25 


7.497 


30 


8.997 


35 


10.495 


40 


12. 







This table shows that 12 inches of etfective rain during 
the growing season of wheat, starting with the soil moisture 
in good coiiditi(m, should enabh^ a yield of 40 bushels per 
acre to be produced. 



141 



169. Least Amount of Water Which Will Permit Yields 
of Different Amounts. — In tlui next tahle there is given the 
k'ast aiiiouut of water taken from the soil which can be ex- 
pected to ii'ive tlie yiehls for tlie different crops there stated : 

This talilc must lie reuarde*! as showing \\w. minimum 
amounts of water wliich will hi'iug tlie crops named to 
full maturity so as to produce the yields specified nnder 
conditions of ahsolntelv no loss bv surface or nnder-drain- 
age, and where the evaporation from the soil itself is as 
small as it can well be. Jt must be farther nnderstood that 
the soil at seeding tiiue already ])ossesses the needful 
amount of water foi' tlie best couditions, and that at the 
end of the growing season it is \'et so moist that no check 
to vigorous, normal growth has occurred. 



Table shoiving the highest probable duty of ivater for differ' 
ent yields per acre of different crops. 



Bushels per acre 


15 


20 


30 


40 


50 


60 


70 


80 


100 


200 


.300 


400 


Name of crop. 


Least number of acre-inches of water. 


Wheat 


4.5 


6 

4 28 

■i.im 

3.36 
.41 


9 

6.42 

5 701 

5.34 

.62 


12 

8.56 

6.272 

6.72 

.83 


15 
10.7 

7 84 
8.4 
1.03 


18 
12.84 

9.40 
10.08 

1.24 














Barlev 


19.98 
10.98 
11.75 
1.45 












Oats 


2.35 
2.52 


12.54 
13.43 
1.65 


15.68 
16.77 
2.07 








Maize 










4.14 


6.2 


8 27 








Tons per acre . . . 


1 


2 


3 


4 


6 


8 


10 


12 


14 


16 


18 


20 




Least number of acre-inches of water. 


Clover liay, 15 
percent, water 


4.43 
2.08 
1.41 


8.85 
4.16 

2.82 


13.28 
6.24 
4.23 


17.7 26.55 


35.4 
16.61 
11.28 


44.25 
20.72 
14.1 












Corn with ears, 
15 perct. water 

Corn silage, 70 
per cent, water 


8.32 
5.64 


12.47 
8 46 


24.95 
16.92 


29.1 
19.74 


33.26 
22.56 


37.42 
25.38 


41.58 

28.2 



142 



CHAPTER YI. 
PHYSICS OF PLANT BREATHING AND ROOT ACTION. 

MECHANISM AND IvrETIIOB OF TRANSPIRATION IN PLANTS. 

170. Breathing- of Plants and Animals. — The transpira- 
tion of plants and the respiration of animals are processes 
which have nineh in common. Both plants and animals 
are j)rovided with internal cavities into which air may en- 
ter. They both breath air. While breathing air both give 
off large quantities of moisture. The primary object of the 
lungs is to supply the body of the animal with oxygen and 
to remove carbon dioxide. The corresponding structure in 
the leaves of plants is to supply it with carbon dioxide and 
to throw off oxygen. In both cases the breathing surface 
has a very delicate texture and is situated where it can al- 
ways be kept wet ; the chief function of the water escaping 
from the breathing surface is to keep it moist. 

If the lining of the lungs were to become dry and 
parched the gases would not as readily pass through and 
there would be like difficulty in the case of leaves, if their 
breathing surfaces were not kei)t moist. In both plants 
and animals the breathing surfaces are carefully guarded 
from the intense sun and strong drying winds. 

171. Respiratory Organs in Plants. — The air passages or 
breathing chambers of plants are chiefly located in the 
leaves, but they are also found to greater or less extent in 
all the green parts. They are simply irregular chambers 
left between the cellular tissue and are represented in the 



14:] 



lower ])orti()n of Fig. 42, which shows a section of barley 
leaf with the epidermis removed and nmch magnitied. 

172. Breathing Pores. — Leading into tlie air chambers 
are many hi'cathing pores through which the air enters. 

Eight of these are repre- 
sented in Fig. 42. They 
are most nnmerons on the 
nnder sides of leaves 
where evaporation may be 
least. 

The breathing pores or 
stomata are very small 
and nnmerons, Weiss es- 
timating, from an average 
of 40 |dants, as many as 
2()1>,0()() in each square 
centimeter of surface, an. 
i area equal to the square 
shown in Fig. 44. The 
In the case of a corn leaf 
2 1 per cent, of the surface 
^ci?io^^^ occupied by the door- 
Avays to the breathing 
chambei'S. 




Fig. 42— Structure of bar]e,v ]eaf. 
Sorauer) so is a breatiiiug pore ; ni. 
rophyll cells; i, respiratory cliainbers 



173. Chlorophyll Cells. — Surrounding the air chambers 
in every leaf there are multitudes of tender, thin-walled 
cells in which are found the green chlorophyll grains, giv- 
ing color to the leaf, which absorb the sunshine and use it 
in breaking down the carbon dioxide for the carbon, which 
is one of the chief constituents of plant tissues^ and of the 
stai'clies, sugars and most otlicr compounds. 

174. Guard Cells. — In order that the loss of water may be 
as little as ])ossihh' each l)reathing ])ore is surrounded by a 
pair of guard cells, represented in Fig. 42, and on a much 
larger scale in Fig. 43. These guard cells have for their 
function the regulation of the amount of evaporation from 



144 



the plant. Tlic chlorophvll <2,riiiiis can hr cft'cctivo in 
breakiiiii' down the carbon (lioxi(U' only in c()ni])aratively 




Id 000 



Q DC^I 




B D 



Fig. 43. — Dhini'.-mi sliowiiiji- the inei-hiuiical iK-tiou of Kn.-ird cells In opoii- 
ing and closinji- lircitliiuf; poros. Tlit' sqiiiirc shows the wvvw of 
un<l<"r side n( IcMf <-ontaiiiinfi' ;ni avt'i-n^-.' of L'IIK.IKHI hrcal lun;;- pores 
or sroni;ila. (l-'mm Irriiratioii and I »raiii:i,i;-e. i 

bright liiiht and so, durinii' clondv <hi_vs and at ni<2,ht, the 
guard cells autoinatically change their form and close the 
doors, reducing eva])oration. ]n(h'ed they renuvin open 
only when there is light enough to utilize it in decomposing 
the carbon dioxide. 



175. Action of the Guard Cells. — 'Phf opening and closing 
of the guard ctdls is brought about by their peculiar shape 
and changes in the amount of material they contain. 

Unlike the other cells in the epidermis of the leaf these 
contain chloroi)hyll grains and are thus able to carry on the 
process of developing plant food. The advantage of hav- 
ing this work done here is to increase the osmotic pressure 
through the rendering of the sap denser wheii the sun is 
shining, thus distending the cells and changing their shape 
so as to open the doors widest when the sun shines brightest, 
as represented at A, Fig. 43. When night comes or it is 
cloudy then the osmotic pressure-' forces the assimilated ma- 
terial out of the guard cells faster than it is produced and 
the walls collapse, taking the attitude represented at C and 
in cross section at I), closing the o])ening. B and D are 
cross sections of a pair of guard cells along the lines 1-2 
and B shows how a full cell must pull the edges a])art while 



145 

D slicnvs liow tlie liiup condition will permit the walls to 
fall toii'cthcr. 

176. Loss of Water Through the Guard Cells. — Tlu; epi- 
(Ic'i'niis of the leaf is so el(^se in texture and often so water- 
proofed that when the guard cells close there is but little 
loss of moisture. But Avlien the sun shines and there is 
moisture enough in the soil to keej) the leaves from Avilting 
the guard cells open wide and great evaporation may take 
place even in a saturated atmosphere. 

By admitting li^■e steam into our plant house on bright 
sunny days, keeping the air highly saturated, we have 
found corn to lose nearly as much moisture as in the dryer 
condition of the air with the sun also shining. The reason 
this is ])ossible is that the epidermis acts like the glass of 
the hot bed, permitting the sunshine to enter but preventing 
the longer dark heat waves from escaping. In this way 
the air saturated outside is not so inside on account of the 
higher temperature. This remarkable provision of the 
plant to save moisture should teach how important it is to 
assist, in every way practicable, the conservation of soil 
moisture. 



STRUCTCKE AND :S[ODE OF EOOT ACTIOX. 

There is scarcely a better illustration anywhere in 
JSTature of the adaptation of living organisms to their en- 
vironments than is furnished by the mechanism by which 
the higher land plants supply themselves with moisture; 
and one of the most remarkable of remarkable tasks is that 
of a corn plant pumping into its stem and leaves, from a 
comparatively dry soil, 2. 800 pounds of water daily for 13 
consecutive days. 

177. Functions of Roots. — The roots of ordinary land 
plants have three distinct functions to perform: First, to 
gather from the soil its moisture and the salts dissolved in 
it for the use of the plant ; second, to convey and deliver 



146 



into tlie stem and leaves the water al)sorl)e(:I ; and third, to 
act as an anchor or support, holding the plant upright in 
tlie soil, air and sunshine. 




Fif!. 44.— A. Koot-liiiirs of iiaistanl pl.-nits. witli snil adlu'i-inu'. and wiih 
soil removed. H, rool-liairs ut' wheat, when \ ery yoiinj;-, and fonr 
weeks later. (After Saelis.) 

178. The Absorbing Portion of Roots. — It is the general 
belief of jdant ])livsi()logists that the active portion of roots 
— that wliicli is iniiuediately concerned in gathering the 
water from the soil — is what are known as root hairs, rep- 
resented at the k'ft of A, Fig. 4:4, and at A buried in the 
soil grains in the same figure. In Fig. 46 is a much en- 
larged view of a single root hair which has worked its way 
in among the soil grains where it is in place to absorb soil 
moisture and soluble salts. The appearance of root hairs 
in relation to soil grains can be clearlv demonstrated by 
growing plants in rather coarse sand between glass plates 
as represented in the api)aratus shown in Fig. 45. 



147 



179. Structure of Root Hairs. — R(X)t liairs are extremely 
thin Availed and lireatlv leii^tlieiicd single cells, having 
lengths ranging nj) to an eighth (U- qnarter of an inch and 

a diameter of liu of an 
inch. They stand (jnt 
al)()ut the main root like 
the pile of velvet, forming 
a hrnsh-like appearance as 
shown in Fig. 44. The 
(thjeet of this form is to 
secure a large area aronnd 
which surface tension may 
force the water in the 
same way that it does 
about the soil grains. In- 
dee* 1 root hairs have forms 
adapted to drawing upon 
themselves a portion of 
the water film investing 
tlie soil grains. 

180. Relation of Root 
Hairs to Soil Grains. — The 

manner in which root 
, , . , ,, hairs i^lace themselves 

Fig. +r).— Apparatus tor nbservine; the Rrowtu ^ „ . . 

of roots and tlieir relation to soil grains. amOng the SOll gramS IS 
The sides of tlip apparatus are two panes , n i • j.a jr 

of glass, 1.5 inches apart. dearly shown in the lorm 

of a diagram in Fig. 4(; where h h is a root hair; e is the 
main root, -2 a soil grannie, and 1 an air space; while the 
concentric lines represent the tilms of capillary moisture 
which surround both the grannies and the root hairs. In 
Fig. 47 is represented the tip of a young growing root ad- 
vancing into fresh soil and having five root hairs developed 
in place among the soil grains ready for Avork. 

181. Method by which Root Hairs Gather Water. — As the 
root hairs force their way through the pore s})aces among 
the soil 2:ranules they lu'ing their walls into close touch with 




148 



tliem in such a wav that in form and position thev make 
lip a part of the soil mass. In this relation the force of 
adhesion draws the capillary water out over their walls so 




Fig. 46. — liistribulioii of water 
root-hnirs. e, main root: 1, air 
h li, root hairs. (After Sachs.) 



if soil grains and of 
ain; 3. film of water; 



as to leave them and the soil granules surrounded l)y the 
water film. Each root hair is or should be in a sense under 
water, that is invested in a film of greater or less thickness. 
When a portion of this water enters the root hair and 
passes on into the root and up to the leaves, the water layer 
surrounding the root hair is left thinner ; but no sooner 
does this thinning out occur than the equilibrium is de- 
stroyed and surface tension at once squeezes more water 
onto the surface from the surrounding soil. In this way 
capillarity keeps the water moving to the root hairs as they 
pass it on to the plant. 

182. Advance of Roots through the Soil. — Until the 
method by which roots advance tlirough the soil is under- 
stood it is difficult to realize how it is possible for such deli- 
cate structures to set the heavy soil aside sufficiently to 
reach the great depths they do. ^Nature's method of over- 
coming the difficulty is simple enough and it is as effective 
as it is simple. The large amount of open space there is in 
the surface four to six feet of soil makes it easier to set the 



140 

soil aside, aii'l tlic sctiini; <'i fence posts jtfoves how large 
this space is. A (i-inch post set in the hole dug for it seldom 
occupies so iiinch of the space hut that all of the soil re- 
moved rnav he returned ]ty tlionnigli raniuiiug. It is the 
existence of such hiri;c ainoiinis of open space in the soil 
which nuikes the iMo\enients of water, air and roots 
throTigh it possihh' nnd the ahseiiee of it which makes a 
puddled soil so uncongenial to plant gi'owth. 




n 



Fig. 47.— Method liy wlncli idol li:iirs :ulv:nice throusli tlio soil. 

(Aihiptod Iroiii Sachs.) 

In Fig. IT is vej)resented a section of the tip of a root 
growing and advancing through the soih It has been 
found that at 1, a short way hack from the tip, tiiere is a 
center of gi'owth. Here new cells are forming by division 
and sul)se(pieiit enhirgenient. On the forw^ard side of this 
cell the new ones l)ni]d the root ca]), which acts as a shield 
and wedge, while those in the rear are finally transformed 
to make the various structures found in the root. 

At the ccMiter of growth new c(dls are forming and ex- 
panding under the intense power of osmotic pressure and, 
as the root is anehored heliind, the ro(->t cap is pushed for- 



150 

"vvarJ and wedged sidewise, setting tlie soil aside and thus 
making room for itself. The root oa]) does not slide for- 
Avard j)ast soil grains but is anchored rigidly to them; the 
tip entering existing cavities is enlarged by growing for- 
ward under and through the ca]i, the rear cells of which die 
after the root has grown |)ast them, the root cap being a sort 
of point continually renewed as tiie root advances. 

183. The Extent of Root Development of Corn. — It is only 
by careful study that the extent of root development in a 
soil can be learned. In Figs. 48 and 45) are shown the 
amount and distribution of corn roots at two stages of 
e-rowth. When the corn was 30 inclies hiiih the whole of 
the soil to a de])tli of two feet was as full of roots as the 
engraving shows between the two hills ; when the corn was 
coming into tassel the roots had penetrated to a depth of 
three feet and bad come closer to tbe surface ; and at ma- 
turity the roots had reacluMl four feet in depth, making 
their way through a fairly lu avy chiy loam and clay sub- 
soil, the fourth foot only being sandy. 

It should be understood that the roots here shown grew 
in undisturl)ed tield soil and were obtained by going into 
the held at the stage of growth shown and digging a trench 
around a block of soil a foot through and the length of the 
Avidth of the row. The cage was then set down over the 
block; wires run through the block of soil to hold the roots 
in place and then the soil washed away by i)umping water 
in a hue sju'ay upon the block. Iliree days' work for two 
men were recpiired to secure the sani])le in Fig. 40. 

184. Extent of Root Development of Grain. — In Fig. 50 
is represented the depth to which the roots of winter wheats 
barley and oats penetrated a heavy clay soil and subsoil. 
The roots are what were found in a cylinder of soil just 
one foot in diameter and were obtained by driving a cylin- 
der of metal four feet long its full depth into the soil and 
then washing the dirt out of it. It will be seen that in each 
case the roots have reached a (lej)th of fully four feet. 



151 




Fig 



-Shi)\vin<; .iiiKiiint ;iml ilislrilmtidii of c-m-ii I'outs under natural 
licld I'liiidil ions. 



i:.2 




Fir,. 49. — Sliowiiii; Miiioiint iind distribution of funi roots timlor natural 

lield C'onilitiuns. 



-1 - o 

1 .) ■) 




Wheat. Barley. Oats. 

Fig. 50.— Showing amount of roots found in tlit^ fit'ld in .-vlindcr of soil 
one foot in diuDK-tcr, fxteniiny to a depth of four fci-t. 



154 




Kic. 51.— Slidwiiif; llic t(it;il runt of one hill of cnni. 




Fig. 52.— Showing total roots of Dat.s. 



l.-iG 




Fi<;. .W.-Sliowiiii; lutjil rcKits of mcdhiin clover. 



157 

The coarse branches sliown with the winter wheat roots 
are tlie roots of a red oak tree which was growing in a 
pasture 33 feet away, and they serve to show how far forest 
trees send their roots foraging through the soil for water 
and food, and through what long lines the water must be 
j»innp('(l after it has been gathered. 

185. The Total Root of Plants. — In the preceding sections 
tlie sani2)les simply show the amount of root found in a 
given volume of field soil. In Fig. 51 is sliown the total 
root of four stalks of corn, while Figs. 52 and 53 show the 
same thing for oats and medium clover. These were se- 
cured by growing the ])hints in cylinders 42 inches deep 
and 18 inches in diameter, lilled with soil. When the 
crops were mature the cylinders were cut down and the soil 
Avaslicd away. 

In each case the roots ext(;nded to the bottoms of the 
cylinders, forming a dense mat there, as the engravings 
show. 

The roots shown with tlic <'lo\'er, and which gathered the 
moisture for the top, forccid fi'om tlie soil water enough to 
cover the si)a('{' to a depth of 29 inches. It will be seen 
that the stand of clover is very close, fully three times as 
heavy as a good clover crop in the field. This was made 
possible by having a rich soil and suj^plying all the water 
the plant could use at just the right time. 

The length of all these roots is less than it would have 
been had the cylinders been deeper, as proven by the mat- 
ting at the bottom. 



158 



CIIArTKK \U. 

MOVEMENTS OF SOIL MOISTURE. 

186. Types of Soil Moisture Movement. — The moisture 
wliicli is foniitl in the soil above tlie surface of the croiind 
water is coiitiimally subjected to tliree types of movement : 
(1) Gravitational,'^ (2)'Capinary and (3) Thermal; the 
first due to the action of gravity, the second to surface ten- 
sion and the third to heat. 

AVhen rain falls upon the soil one portion of it begins 
to flow vertically downward through the pore spaces, urged 
to do so by the pull of gravity ; a second portion increases 
the thickness of the water film surrounding the soil grains 
and root hairs and is made to do so by surface tension ; 
while a third portion is returned to the atmosphere through 
evaporation, caused by heat. 

GRAVITATIONAT. MOVEMENTS. 

187. Percolation of Soil Moisture. — The diicet gravita- 
tional flow of soil moisture, which occurs during and after 
rains, is nearly always vertically downward until the 
ground-water surface is reached. The movement takes 
place chiefly through the shrinkage cracks and passage- 
ways left by the decay of roots and the burrowing of ani- 
mals, but also through the capillary pores formed by the 
grains of the coarser soils and by the granules of the finer 
types. 

The rate of movement is most rapid following heavy 
rains when the soil is already well saturated. After pro- 
longed periods of drought, when the soil has become very 
dry, there is so much air in the pore spaces that it greatly 



159 

impodos percolation oxccpt in those cases where wide 
shrinkage cheeks and cracks have resulted. 

Where percolation is influenced chiefly by soil texture it 
is most raj)id through the sandy soils and the more granu- 
lated clay types. It is least rapid through the puddled 
clays. 



188. Rate of Percolation Through Sands. — When the sim- 
ple sands are once completely iiUcd with water the perco- 
lation from them is quite rapid but decreases with the size 
of the sand grains. In the table below is given the 
amount of wat(M- which percolated from the columns of 
sand rcfcn'cti to in ( 160). 

Table (jiving the rate of percohdion frohi aaruhs under the 
prnvitational head of the inclosed tvater. 



Geade of Sand. 



No. 20. . 
No. 40. . 
No. 60. . 
No. 80.. 
No. 100. 



Eil'ectivo 


Per cent 


Wcierht 


diameter 


of pore 


of sand 


of grain. 


space. 


per 8 cu- 
bic feet. 


m. :n. 




Pounds. 


0.474.5 


H8.86 


809.28 


.1848 


40.07 


793.28 


. 1551 


40 76 


784.00 


Aim 


40.. 57 


786.64 


.0826.5 


39.73 


797.76 



Amount of Watee Pbeco- 

I^ATED IN — 



First 30 min. Second 30 min. 



Lbs. 

.53 3a 
39.27 
29.99 
7.86 
6.31 



Indies. 

10.?.5 
7. 549 
5 674 
1.512 
1 213 



Lbs. 

24. K6 
27.35 
23 .^2 
6.73 
4.40 



Incbes. 

4.683 
5.2,58 
4.. 522 
1.294 
.815 



It will be seen from the above table that the rate at which 
the water moved downwai'd thi'ough the coarsest or Xo. 20 
sand was such as to average during the first thirty minutes 
492 inches per twenty-four hours, while for the finest or 
"No. 100 sand the mean rate was 58.16 inches, the flow 
from the first being nearly 8.5 times as fast, with grains 
not quite 6 times as large. 

After the end of the first nine days of percolation these 
coarse sands lost about 1.7 per cent, of their dry weight in 
each case, or only about .33 of an inch. 

189. Rate of Percolation from Soils. — 'llic jK'rcolation of 
Walter from the sandy loam and from the clay soil, given 



IGO 



in tlic hililc (if (160), AvluMi tlio ciglit-foot coluiiiiis M'cre 
eoiiiplctclv full of Wiitcr at the start, took ])la('C at a much 
slower rate than from the sands, as indicated in (188)^ the 
rates beine' 





SmihI.v 
loam, 
iiiclios. 


Chxy 

loiuii 

inciies. 


First 21 hours. . 


2.640 






1.958 


First 10 <ltt,vs followiiiK tlio above . . . ^ 


5.072 
.905 

8.617 


2.111 

.49;j 








4.562 







'I'lie rates in these cases were such tliat more water per- 
colated from the three coarsest sands during the lirst 30 
minutes than iVoni the clay loam in as many days; and jet 
the loam contaiiie(l at tlu^ start tlie hirgest amount of water. 
It is clear from thes(> difl'ei-ences in the rate of ])ercolation 
M'hy the sand could not he produ(!tive under ortlinary con- 
ditions of I'aiiif.ill, no matter how miicli plant food it might 
contain. It is ch'ar also that tiuencss or closeness of tex- 
ture is one of the most iui|»ortant qualities of a good soil, 
for without this \]u) water (.trains away so ra])idly that, 
Avith tli(^ ordinary intervals between rains, not eiKUigh could 
be retained for the ne(Mls of crops. 

190. Percolation Through Dry Soil.- When soils have 1h^- 
come relatively dry, as happens especially during the mid- 
dle and later summer, Avater docs not percolate into them 
as readily as it does in the spring Avhen the pores are more 
nearly tilled. AVhen the volume of air in the soil is large, 
and Avhen the films of Avater surrounding the soil grains are 
very tliin, the How downward ])ast the air is V(>ry slow. 
It is on this account, in part, that the lighter rains arc less 
effectiA'o in midsummer than they are in the spring, the 
Avater being retained close to the surface Avhere it is quickly 
lost by evapoi-ation. 



161 



CAPILLAKY MOVEMENTS OF SOIL MOISTURE. 

The capillary movements of soil moisture are relatively 
slow, when compared with those of percolation, and are 
slower in dry than in wet soil. 

The general tendency of capillarity is to bring water to 
the surface from varying depths, but its movements may 
occur in any other direction, the flow being always from a 
soil where the water films are relatively thick toward those 
where they are thinner, or from the wetter toward the 
dryer soils. 

If the roots of plants have made the soil dryer in their 
immediate neighborhood capillarity may carry water to 
them from below, above or from either side. When heavy 
rains follow a dry spell then capillarity will assist gravity 
in carrying the water more deeply into the gTOund; and 
when water is applied by the furrow method in irrigation 
capillarity carries it laterally away from the furrows. 

191. The Rise of Water in Capillary Tubes. — When a 
clean glass tube whose bore is small and wet is held verti- 
cally in water the liquid rises to a certain height above the 
level outside, the amount vai-ying with the diameter of the 
tube, as given in the table below : 

In a tube 1. inch in diameter the water raises .054 inches. 
In a tube .1 inch in diameter the water raises .545 inches. 
In a tube .01 inch in diameter the water raises 5.456 inches. 
In a tube .001 inch in diameter the water raises 54.56 inches. 

That is to say, reducing the diameter of the tube one-half 
doubles the height the water may be raised by capillarity, 
and reducing the diameter to one-hundredth enables the 
water to rise 100' times as high. The results in the table 
above will be true only when the walls of the tube are very 
clean, the water pure and the temperature 32° F. 

192. Cause of the Variation in Height to Which Water Is 
Haised in Capillary Tubes. — The reason for the differences 



1(1:3 



ill li('ii;lit to uliicli \\;itcr m:iv he niiscd in cnpillary liiluvs 
by siii-fiicc Iciisidii is loiiiid in tlic I'cliilioii cxisliiiii,' Ix'twcen 
tli(> \(ilniiic of lilt' tnl)(' ;in(l ils iiilcrinil circnin rcrcnco at 
the lr\cl (if llic wnlcr snrfnci'. (j)nink(' liiis sliowii tliilt 
the force ol' collision is c\crtc(l o\'ci' a dislancc of non'ooo 
incli ; so lliat wlicii a i^lass liihc is llinist. into water llio 
molecules in the surface of llie wall just al)o\c llic water 
draw upward npon the rows (d mioIccmIcs in IIk^ stirlaco 
l\ini;' nearest, raisiiii;' llieiii ahoNc llie natural waler l(>V('l. 
r.iil as I lie edii'c <d' t lie surface til in is raised llie whole water 
coliiinn is carried iijiward also until I In* wcii;lit lilted aliovc 
tlie liN'drostat ic le\'el is e(iiial to tlie coliesi\'e attraction be- 
tween I lie liiass and the water. 

As eacli niolecnle of ulass has a li\ed power to pull, the 
tulte (d' lariic dianieler will he ahle to lift as iiiiich iiior(! 
water than the small one, as llie nninhrr (d' luoleciiles in 
its eircnmlerence is i;reater. Hut the circiim fereiices of 
liihes increase ill the same ratio as their diameters, and 
hence a Inhe whose dianieler is .1 inch will lift above tlio 
water level H» limes as iniicli waler as the (Hie .01 inch in 
dianieler. Init, as the weight <d' water lifled increases as 
lli(* s(piares (d' the diainelers (d' the liihes, the lirst liilio 
will oiiK lift, ils coliiinn one tenth as liiiiii as tli(> second. 
Inhe, for then ils load hecoiiies 10 limes as ii,reat, and this 
is llie limit id' ils power, as expressed in the laMe helow : 



nianu'tiM- (if tiibo. 



Rolntivo area 

<>r (M'OSS- 

sootioii of 

til 1)0. 



H«idit to 

wliicli \vat(^^ 

i.-i lift 0(1. 



Holativo 
aiiioiiiit of 
wator liftoil. 



1,0 inch. 
.1 iiicli. 
.01 inch. 
.001 iuoh. 



1,(HK),0(K) X .O'VtSO inchos - .'i4. 560.00 

10,(1(10 N .ru^ii iiidios - 5,466.00 

10(1 X 5.456 inchos - 546.00 

1 X 51.560 inchos = 61.56 



The actual ainoiint itf waler lifled hv the surface" film 
slrelched across tlu> Inhe and carried iii)ward hv tlio 
{)ull (d" lli(> ii'iass niolecnles just ahove ils ediic is as fol- 
lows : 



Hj'S 



In the 1.0 inch tube 04285 cubic inch. 

In the .1 inch tube 004285 cubic inch. 

In the .01 inch tube 0004285 cubic inch. 

In the .001 inch tube 00004285 cubic inch. 

193. Capillary Rise of "Water in Soils. — U'lie spaces left bc- 
tweuii tlic soil grains funii more or less triangular capillary 
tubes whose cross-section, formed b_v four spherical grains, 
])lace(l as closely together as possible, is represented at the 
left in i'ig. 54; and these tnbes extend in all directions 
tlirongh a soil. 

The effective diameters of these capillary tubes are 
somewhat nearly proportional to the diameters of the soil 
grains so that for soils with spherical grains having the 
closest jDacking, doubling the diameters of the grains would 
also double the effective diameters of the capillary tubes 
thronch which the water must bo moved. 




'J'hs ai-ea of cross section of the two capillary pores 
.-;ho\vii in Fig. 54 is equal to the area of the rhombus con- 
necting the centers of the four grains minus the area of a 
circle having the diameter of tbo soil grains, so that divid- 
ing this area by two gives the area of the section of the 
pore. 

Where the pore has the smallest section its area is given 
by the equation 

Area = ("/S — ^) X r* = .1613 r« 

where r is tbo radius of tlie soil gTain. 



1G4 



Tho capillary pores in nii ideal soil do not have a uni- 
form diameter but are shaped like the cast shown in Fiff. 




Via. 55.— SliowiiiL;- a cast of ihc i»or.> spare botwoou siiluu'ical grains, 
much cnlarfii'd. 

55, largest at one place and decreasing in. either direc- 
tion to the area given bv the equation above. The mean 
area of the section of the pore, is given by Slichter,* as 
mean area of section of pore = 0.2118 r- 

Avhieh Avould nnike the largest or effective cross section 
of the ca]>illary pore not far from 

( .2118 X 2) — . 161.3 = .2623 r- 
From this the effective diameter of the capillary tubes 
may be found, using the formula 

P^, ^ \2623r^ 

whore r is the radius of the soil grain 
and D is the diameter of the capillary pore. 



* Theoretical Investigation of the Motion of Ground Waters, 19th 
annual report of the Geological Survey, part II, p. 316. 



165 

On this basis spherical soil grains of one size and the 
•closest packing, having diameters of 



m. m. 


m. m. 


m. m. 


m. m. 


m. m. 


1. 


.5 


.1 


.05 


.01 



wonld form capiUai-y tnbes whose largest cross sections 
arc nearly ecpiivalcnt in area to circles having diameters of 

m. lu. m. ru. m. lu. m. m. m. m. 
.289 .1445 .0289 .01445 .00289 

Did such soil grains hav(^ the attractive power of glass 
for water and w^ere their triangnlar pores capable of rais- 
ing water to the height of circular tubes of equivalent 
cross sections they should be able to lift water at 32° F. 
to very nearly the height of 

.4 ft. .8 ft. 4 ft. 8 ft. and 40 ft. respectively. 

194. Observed Height of Capillary Rise of Soil Moisture — 
To measure the rise of water by capillarity in ordinary 
soils four cylinders, 10 feet long and .04611 sq. ft. in sec- 
tion, were iillod, two with a sandy loam and two with 
a clay loam, the first containing 18.88 per cent., and the 
second 32.63 per cent, of water uniformly distributed 
throughout the columns. On one of each set of tubes a 
soil mulch was developed 3 inches deep, when they were 
all placed in front of a ventilator where a current of air 
was maintained across their tops during 314 days. At 
the end of this time the tubes were cut into 6-inch sec- 
tions and the water content of the soil determined, with 
the results given in the table which follows : 

It is clear from this table that there has been an up- 
ward movement of Avater and loss through the surface 
even from the bottom layers of soil in the case of the 
medium clay, and probably also from the sandy loam. 
This follows from the fact that the clay soil contained, 
when put into the cylinders, 32.63 per cent., whereas the 
lower six inches is 1.38 per cent, drier in the mulched cyl- 
inder and 3.17 per cent, drier in the cylinder not mulched. 
10 



166 



Table showing the loss of water by surface evaporation from, 
columns of soil 10 feet long, mulched and not mulched. 





Sandy Loam. 


Clat Soil. 




Mulched 
3 inches. 


Not 
nnulched. 


Mulched 
3 inches. 


Not 
mulched. 


Surface 6 inches. 


Per cent. 

8.83 
12 97 
14.59 
15.25 
15.55 
15.89 
16.22 
16.29 
16.58 
17.07 
17.05 
17.26 
17.56 
17.78 
17 94 
17.96 
18.25 
18.67 
18.. V3 
19.21 


Per cent. 

7.41 
14.48 
14.70 
14.96 
15.53 
16.17 
16.33 
16.33 
16.10 
16.76 
17.31 
J7.43 
17.79 
17 88 
17.85 
17.67 
18.05 
18.09 
18.63 
19.95 


Per cent. 

17.66 
24.59 
26.58 
26.95 
27.45 
27.92 
27.94 
28.24 
28.46 
28.47 
28.87 
28.70 
29.24 
29.28 
29.33 
29.79 
30.32 
31.15 
30.47 
31.25 


Per cent. 

7.79 

18 30 




21 46 




26 26 


24 iuche.s to 30 inches 

30 inches to 36 inches 


26.89 
27.16 
27 61 


42 inches to 48 inches 


27.64 




27 28 




28 23 


60 inches to 66 inches 

66 inches to 72 inches 

72 inches to 78 inches 


27.79 
28.05 
i'8.93 
28.31 




28.32 


90 inclies to 96 inches 

96 inches to 102 inches 


28.80 
29.14 
29.16 


108 iuclies to 114 inches 


29.33 


114 inches to 120 inches 


29.46 



In the case of the sandy loam the lower six inches in each 
case is wetter than when it went in, showing that at first 
percolation downward had taken place, and as this soil 
when allowed to drain freely only retained 19.44 per cent, 
of water at a depth of 36-42 inches, it is qnite probable 
that at some time the lower soil 10 feet below the sur- 
face may have been wetter than found at the end of the 
trials, and if this is true then even, the sandy loam has 
lost water upward from a depth of ten feet below the sur- 
face. 

It is quite certain that a drying- of these soils has taken 
place through a depth of ten feet, and hence that moisture 
ten feet below the surface of the ground may become 
available for vegetation purposes at or near the surface. 

The effective diamet-er of the soil grains in these two 
cases was found to be, for the sandy loam, about .01635 
m. m., and for the medium clay loam, .01254 m. m. ; thish 
would indicate that there might be a capillary rise of 23.6 
and 30.8 feet respectively. 



10" 



195. Capillary Kise of Water in Sand. — In the case of a 
sorted sand witli grains .4743 m. ni. in diameter, when 
saturated Avith vrater in an apparatus represented in Fig. 
;■)(), it Avas found that water was raised through a col- 
umn 6.75 inclies above the level of water in the reservoir 
at the rate of 44.09 inches of water on the level per 24 
hours, hut that when the column was made 11.75 inches 
lone no water was raised to the surface. 



1 



n. 



I 



Fif;. 56. — Apparatus for uicasuriiij;- the iiiAxiuuun rate and lu'ijrht of 
capillary rise of water in s.-mds. A, evaporatiiin' reservoir; I!, water 
reservoir; (', rui)l)er tiiV)e. 



From the formula in (193) a glass sand with grains the 
size of this one should be able to lift water by capillarity 
to a height of 10.11 inches and, since the quartz sand used 
did lift water at the rate of 44.0 J) inches in depth in 24 
hours through a height of 6.75 inches, and failed to lift 
any water to a height of 11.75 inches, it is clear that its 
majcimum limit must lie very close to that computed for 
the glass sand. 



1G8 



196. Rate of Capillary Rise of Water in Wet Soil. — There 
is yot no very .satisfiU'torv data, as to just how rapidly wa- 
ter may Ix^ luoved by ea])ilhirity through wet soils. It is 
])robal)l(' that the case cited in (195) represents abont the 
nia:xiMiuui rato in that coarse cpnirt/ sand, throng'h that 
lieiglil, nauudy, 41.()!> iucdics in (l(']»tli ]>er 24 'hours. This 
is an (niornious quantity of water to be raised by capil- 
larity and was rendered |)ossibl(' only by expanding the 
column of" sand at the lop, as shown in the figure, so as to 
increase the rate of cNaporat ion until it exceeded the abil- 
ity of ca|>illai'ity to bring the water to tli(> surface. 

Experiments ha\'e shown that with a strong current of 
air passing aci-oss the wet surface oi the soil, water was 
lifted by capillarity at the following rates: 

From a squan^ foot, of soil, water was lifted through the 
different <listances and at the rates given in the table be- 
Iqiw : 



Fine quartz sand 
Clay loam 



1 foot. 



lbs. per day. 
2.37 
2.05 



feet. 



lbs. per day, 
2.07 
1.32 



■.i feet. 



lbs. per day. 
1.23 
1.00 



4 feet. 



lbs. per day. 
.91 
.90 



It is (piite certain tluit tlu'se hgures do not represent the 
maximum rate of capillary rise through these soils; be- 
cause, as the surface of the soil had no greater area than 
tlio se<'ti(vn of the soil column, the rate of rise could not 
exceed the rate of evajioration. 



197. Rate of Capillary Movement of Water in Dry Soil. — 

The movenuMit oi water through a thoroughly dry soil, bj 
ca])illarity, is not as rapid as it is through the same soil 
when wet : the case being analogous to tlie much slower 
id)Sorj)tion o\' watei- l>y a dry (doth or sponge tlian by a 
similar one when damp. 

in, the table whicdi f(dlows is given tlic rate at which 
water I'Utered ,"> cylinders of \vater-fr(H' soil, G inches ill 



1G9 



diameter and 12 inches loii^i;', staiidiiii;- in one inch of wa- 
ter and possessing" the nndisturbed Held texture. The 
cylinders stood in a satnrated atmosphere and the amount 
of water absoi-hcd was (let(M-mincd by weighing every third 
day, the samples Ix'iiig tlic siiiiic (»iies nsed in (158) and 
(159). 

Table showing the mean daily absorption of cap illavfj ivater 
by undisturbed field soil. Cylinders 6 inehes in diameter, 
12 inches long, standing 11 inches out of water. 





Pounds pbh Cubic Foot. 




First 
foot. 


Second 
foot. 


Third 
foot. 


Fourtli 
foot. 


Fifth 
foot. 


Water absorbed during 1st 3 days 

Water absorVied durinK- 2ii(l 3 days 

Water absorbed diiriat,' 3rd 3 days 

Water absorlx-d during 4tli H days 

Water absorbed dtiriiit; r)tli 3 days 

Water absorlx'd diuint,-- til li 3 dax s 

Water absorbi'il durint,' 71 li 3 days 

Water absorbed during 8tli 3 days 


12.50 

2.57 

1.74 

1.33 

.96 

.44 

.12 

.07 


12.42 

2.18 
1.02 
.79 
.59 
.46 
.32 
.25 


9.61 

2 33 
1..-J6 
1.28 
1.16 
1.00 
.69 
.48 


13.. 50 

3.58 
1.71 
.51 
.23 
17 
.10 
.03 


10.73 
2.93 
2.15 
.61 
.16 
.06 
.01 
.02 




19.73 

Per ct. 
32.2 

28.28 

3.92 


18.03 

Per ct. 
23.8 
20.43 

3.37 


18.32 

Per ct. 
24.5 
20 39 

4.11 


19.83 

Per ct. 

22.6 
21.30 

1.30 


16.67 




Per ct. 
17.5 




15.72 




1.78 







From this table it is seen that the amount of water 
absorbed during the first three days was only at the mean 
daily rate of 4.1 C, 4.K5, 3.20, 4.5 and 3.58 lbs. respective- 
ly; after the first period the rate of rise was much less 
rapid and did not equal the rate at which an almost iden- 
tical soil (196) raised water through 4 feet as measured 
by the daily evaporation; and yet the daily rise of water 
of .91 and .90 lbs. per sq. ft. would have been greater 
had the evaporation only been more rapid. In the case 
of the sand of (195 ) ihc water was lifted by capillarity at 
the enormous rat(^ of 22S.(» lbs. ]>er sq. ft. in 24 hours 
while the sandy loam of (194), jdaced under the conditions 
of (195), using the same piece of apparatus, lifted water 
at the rate of 26.02 lbs. per sq. ft. in the same 24 hours. 



170 

In the case of the G-iiich cylinders of soil above, with 
their tops only 11 inches ont of water, the length of time 
reqnired for the surface of the soil to begin to appear 
damp was 

2 days for the fine sand or oth foot. 

6 days for the sand and clay or 4th foot. 

6 days for the clay loam or 1st foot. 
18 days for the reddish clay or 3rd foot. 
22 days for the reddish clay or 2nd foot. 

It is clear from the data presented that the rate of cap- 
illary movement of soil moisture is greatly influenced by 
the water content of the soil. 

198. Capillarity Is Stronger in Wet than in Dry Soils. — It 
follows from (196) and (197) that caiiiUary action in a 
ffiven soil is stroniier when the soil contains a certain 
amount of moisture than it is when that amount is much 
reduced. When soils have thcii' water c(»iiteut so much 
reduced that they begin to h)ok dry, and especially after 
they become air-dry, they act as efFective mulches and 
M'ater will neither rise through them so rapidly nor so high 
the dryer they heeonie, and, if undei' these eonditions, a 
light siiower should fall it might have the effect of leaving 
the surface soil with a greater increase of moisture than is 
represented by the rain which fell. 

199. Rain May Cause a Capillary Rise of the Deeper Soil 
Moisture. — It was observed in 1S8U, wdien determining the 
water content of soils at different depths in the field, just 
before and immediately after rains, that frequently the 
lower soil showed a smaller amount of moisture than it 
had before the rain, wdiile the surface layers had gained 
in water more than that represented by the rainfall. It 
was later shown that, by applying a known amount of 
water to a section of a field, the lower soil became dryer 
while the surface layers had gained more water than was 
added, as shown in the table. 



Table showing the translocation of soil moisture due to ivetting 
the surface. 





Percent, of Water. 


Difference. 


Depth. 


Before After 
wetting. wetting. 


In per 

cent. 


In pounds 
per cub. ft. 


0-6 inches 


14. 

15.14 

16.23 

17.70 

16 76 

15.51 


1 
22.23 
15.71 
15.75 
16.92 
14.41 
15.21 


+ 8. 23 
+ .57 

- .48 

- .7rt 

- 2.35 

- ,30 


+2.873 
+ .199 , 

— .213 

— 347 




12 inches to 18 inches 


24 inches to 30 inclies 

30 inches to 36 inches 


-1.032 
- .132 



The amount of water applied to the surface in this ex- 
periment was 2 lbs. per sq. ft. but when samples of soil 
were taken 26 hours later there had been an increase of 
3.072 lbs. in the surface foot and a loss of 1.Y24 lbs. from 
the second and third feet. Observation showed that a tray 
of soil, on a pair of scales at the place, lost, by evapora- 
tion during the same time, .428 lbs. per sq. ft. ; and, as' 
suming that tlie tield soil lost water at the same rate, makes 
the water to be accounted for 

3.072+ .428 = 3.5 lbs., 

while the total loss from the lower two feet plus the water 
added was 

2 + 1.724 = 3.724 lbs. 



an amount as nearly equal to the 3.5 lbs. as could be ex- 
pected. 

In another trial, adding- 1.33 lbs. of water to the sur- 
face produced the gain, by translocation upward into the 
upper four feet, shown in the next table. 



1T2 





Water Content of the Soil. 


Depth. 


Before 
wetting. 


After 
wetting. 


Change. 


First foot 


Pound.s per 
cu. ft. 
11.78 
15.79 
14.73 
14.03 


Pounds per 
cu. ft. 
14.06 
17.52 
15.58 
15.40 


Pounds per 
cu. ft. 
2.28 
1.73 


Third foot 

Fourtli foot 


.85 
1.37 








6.23 











The interval during- this experiment was one of very 
little evaporation and the adjacent untreated ground gained 
1.21 lbs. per sq. ft. in the same depth. This amount and 
the water added deducted from the gain in the treated area 
leaves the translocation 

6.23 — (1.21 4- i-33) = 3.69 lbs. per sq. ft. 

200. Farmyard Manure May Strengthen Capillary Rise of 
Soil Moisture. — When a soil is treated with farmyard ma- 
nure which has become well incorporated with it, it has 
the effect of causing a stronger rise of the deeper soil 
moisture into the surface three feet, where it is most 
needed in the production of crops. The table which fol- 
lows shows the mean results of experiments aiming to 
measure this effect during three years. 

Table showing effect of farmyard manure in strengthening the 
capillary rise of soil moisture. 





1st fooL. 


2nd foot. 


3rd foot. 


4th foot. 


5th foot. 


6th foot. 


Manured 


Per cent. 

of wator. 

19 88 

18.79 

+1.09 


Per cent. 

of water. 
19.79 
19.33 

+ .46 


Per cent, 
of water. 

18.88 
18.60 

+ 28 


Per cent. 

of water. 
17.29 
17 32 

-.03 


Per cent. 

of watar. 
14.35 
14.63 

-.28 


Per cent» 

of water. 

16.98 

17.13 




-.15 







It is seen here that the surface three feet have in some 
way been maintained more moist, and apparently by the 
manure, at the expense of moisture from below. 



173 

201. Heavy Soil Mulches May Strengthen the Capillary 
Kise of Soil Moisture. — Since capillary action is not as 
strong in a dry as in a well moistened soil it should be 
anticipated that any condition which wonld maintain a 
fair degree of saturation in the surface one to three feet 
of soil would permit it to bring up from below, for the 
use of crops, a larger supply of capillary water. 

On three different kinds of soil, where the ground had 
been cultivated during the season in alternate groups of 
four rows 3 inches deep and 1.5 inches deej>, the distribu- 
tion of moisture, ou July 16, was found to be as follows: 

Table showing the effect of mulches in strengthening the cajnl- 
lary rise of soil moisture. 





1st foot . 


2nd foot. 


3rd foot. 


4 th foot. 


Field No. 1 cultivated 3 inches deep .. 
Field No. 1 cultivated 1.5 inches deep .... 


Perct. of 
water. 
11.30 
9.92 

l.:38~ 


Per ct. of 

water. 

15.57 

15.43 


Per ct. of 

water. 

10 54 

11.56 


Per ct. of 

water. 

11.37 

13.99 


Difference 


.14 


-1.02 


-1.62 


Field No. 2 cultivated 3 inches deep 

Field No. 2 cultivated 1 ,5 inches deep .... 


13.96 
12.98 


22.74 
20.44 


23.39 
24.02 


19.47 
21.34 


Difference 


.98 


2.30 


-.63 


—1.87 


Field No. 3 cultivated 3 inclies deep .... 
Field No. 3 cultivated 1 . 5 inches deep .... 


11.65 
10.65 


17.47 

16.85 


16.44 
17.81 


13.03 
13.32 




1.00 


.62 


-1.37 


-.29 







This table indicates that the 3-inch mulch, by main-' 
taining the surface soil more moist, enabled capillarity to 
bring up from below a larger supply of water; that is, 
the maintaining of a relatively high per cent, of moisture 
in the upper two feet of soil makes it possible, through 
capillarity, for crops to utilize a larger amount of the soil 
moisture which is stored in the deeper layers. This 
view is confirmed by the fact that, in the fields of the ta- 
ble above, the largest yields of corn were in all cases taken 
from, the sTound cultivated 3 inches deep, where the up- 



174 



per two feet of soil eoiitaiiu'd, in spite of the larger crop, 
much more moisture, but at tho expense of that deeper in 
the ground, as shown by the fact tliat in every case these 
soils were drvest in the 8d and 4tli feet. 

202. Firming- the Soil May Strengthen the Capillary Rise 
of Soil Moisture. — When soils have been rendered open and 
loose by ])lowing or other deep stirring the first ertect is 
to permit the loose and o]>(ni soil to become dry, because 
this soil is less perfectly in contact with that below. If, 
after such soil has beconu' dry, it is firmed again the moist- 
ure films will then increase in thickness over the surface 
of the soil grains and, as a result of this, moisture will 
be raised from depths as great as four i'oH to saturate the 
firmed dryer soil. In the table below are shown the 
changes which occurred in the dec^pcM- and sujierficial soil 
layers as the result of rollin<>-. 



Tnhir slioiriug how roJlinq ma}/ strengthen the caplllarii rise 
of soil moisture. 



Depth of sample. 


No. of 

trials. 


Rolled 
ground. 


Unrolled 
ground. 


Change 
produced. 


Surface 2 to 18 inclios 


62 
61 
24 


Per cent, 
of water, 

15.85 
19.49 
18.72 


Per cent. 

of water, 
15.64 
19.85 
19.43 


Per cent, 
of water. 

+ .21 
36 


Surfaco 24 iiiclios 


Surface 36 to 54 inches ... 


-.71 



From this table it is seen that the first effect of rolling 
is to increase the amount of moisture in the upper 18 
inches of soil, but that when sam])le9 are taken deeper than 
18 inclies the total amount in. the soil is decreased. In 
other words, the first effect is to concentrate the deeper 
soil moisture toward the surface. 

If, howcvci-, the soil is loft firmed voi-y long then the 
^\•h(>h' column, to the surface, becomes dryer, until it has 
lost so much moisture that it beains to act as a mulch. 



175 



TIIKK'MAI. MOVKAriONTS OF SOIL MOISTURE. 

Besides the gravitational and capillary movcuients of 
soil moisture there are others due to the molecular vibra- 
tions set uj) in the suil-air and water by the absorbed solar 
energy. 

203. Hygroscopic Soil Moisture. — It is seldom if ever true 
that any solid surface, e\cu when in the dryest air, can 
be found which is not invested with a film of inoisturo 
of greater or less thickness. It is also true that even when 
all moisture has been driven from the surface of a solid 
by drying at the high heat of 200" C, the same body will 
again become coated with moisture when exposed to a 
moisture-bearing atmosphere. Water thus collected on 
the surface of solids is calh^d liy(]yo.^copic moisture. 

204. The Movements of Hygroscopic Moisture. — It Avill bo 
seen that the movements of hygroscopic moisture are the 
same as those of evaporation. The same molecular at- 
traction which causes the ca])inary rise of water in a glass 
tube tends to collect the water molecules, which may be 
moving about in the air, n])on solid surfaces. So when 
a dry sodl is exposed to a damp atmos])here soine of the 
moving water molecules are brought in contact with, and 
retained by, the surfaces of the soil grains. The moisture 
will go on accumulating upon the soil grains until the rate 
of evaporation from them equals the rate of condensation. 
Since the water molecules are atti'acted to the soil grains 
more strongly than they are attracted to one another the 
water in immediate contact with the soil grains cannot 
evaporate as readily as that which is further removed when 
the water films are thick, as they are in a well saturated soil. 

Neither can the innermost layers of molecules adhering 
to the soil grains escape to enter the root hairs of plants by 
osmotic pressure as readily as those from the layers fartlier 
removed, and hence there must always be a certain quan- 
tity of water upon the surfaces of soil grains which neither 



ova])(>riit('s rcntlih' nor ])('('oiii(>s cnsilv iiviiihihlci lo [)limls, 
jiiul I his iiinv lu' rciinrdcd ;is I lie li_vj;-r()sc<)|)i(', inoisllii'c. 

205. Relation of the Diameter of Soil Grains to the 
Hyg-roscopic Moisture. || wns shown in (163) ili;ii wilh 
lh(^ snnic thickness of wnlcr snn-onndina,' ihc soil iiriiins 
the per ccnl. ni' wjitcr \\;is ncccssiiri I v ninch hii;ii('i* 
in Ihc soils hnvini;' Ihc sniiiMcsl soil i^rnins. in (192) is 
liixcn (^)ninckc's ohsci'\;il ion of ihc dishincc nci'oss which 
the foi'cc (d' cohesion is scnsil)le, or .-.(mi'imm. inch. Sinci^ 
lliis ;ill nicl ion (d' Ihc soil for wilier is slroni;-cr lh;ni that 
<d" the walci- I'or ihc water it appears lik(dv thai a hiycr 
(d' water snrronnd inu' the soil i^i'ains, at least as thick as 
this, won Id not he as f ree to evaporate or tii otherwise inovo 
ahoid as that ninch larthcr rcino\'cd from this coht\sivo 
attraction, and if so it. is inipoi'tant to know what per 
C(Mds of s(mI midst ni'c a water tilni of sncli a t hickncss woiiUl 
r(>pr(>scnt. This niav he compnled foi' spherical soil 
U'raius wilh the tormnla 



l'(>r ('(Mit. of \v;ili>r ^= 



TT (d + ^t)-' _ n d" 
6 6 

ff d" s[). gr. 
~ (5 



w liiMH* il iliiiiiuMtM" of soil ^rain in c. in. 
t -• tliickiKvss (if \v;il(>r iilin. 
sp. gr, = tho spocilic -Jiravity of tht> soil. 

Takiiii;' a \-crv line siul ha\in<;- grains with a diameter 
(d" .0(>r>(IS ni. m. and a coarse one with a diamctiM' of .1 
m. m., a lilm id" nioislnre on each, haxini:,' the thickness of 
the rani;t' (d" sensihle cohcsi\(' attraction, as a'iv(Mi hy 
(»)iiincke, woidd make the p(M' cent, for tlic linest soil !2..'M 
hnl for tho coai"S(> soil only .1 1. "■).'). \o crop can siir\'ive in 
soils as dry as these; and air dry soils whose grains rani;'C 
li(M\vi>cn tlit»si- <;iv(Mi will li-entM'ally contain more than these 
amounts of moistnre. It follows from these consideva- 
tions, thcr(d'oi-(\ that what has heen i'(\ii'ard(Nl as the hyi;'ro- 
scopic moistnre is more than that held within the range 



177 

ol' scnsildc (•<ilicsi\(', ;il I nid inn. It, ;i|i|»{!arti clear also that 
IK) liiird and I'asL line can l»<' drawn hclwcen capillary and 
h}'^i'()S('(»j)i(; moislni-c, nor indeed IveUveen cither of those 
and the i-i-avitatiunal water; each must shade by iiiseiisi- 
h\i\ (h\i;,rees into tin; oliuir. 

206. The Amount of Moisture a Soil May Absorb from the 
Air. — The anionnl (d' socalled hy<i,ros(!0])ic moisture a given 
soil iiui\' ;d)S(irl» iVdni ihe air (h'pends ])rimarily r.poii the 
ndative leniper;!! nrc <d' ihc soil and i>\' the air and its de^ 
gre(i of saturation. If llie lenipei'ature of a soil could be 
nniintained eontinually Itdow that of a saturated atmos- 
|)liere above, it would in lime become so fully charged wilh 
waler as to resnll nol oiilv in capillary saturati(»n bill in 
pereolalion as well; and il rre(piently ocKMirs on clear 
nights ill summer, when dews are heavy, that a. thick, loose, 
dry <!iist blaiik<'t: will cool down so much that nioistur<! 
condenses upon il in snilicient (plant ity to iiiak(^ it appear 
damp. Inilced di'W, wherever il. forms, is a demonstra- 
lioii <>\' llie Inilli (d' the stateiiienl made; when it evapo- 
i-ates wilh the rising of llie sun llu; loss of moisture from 
tin* blades (d" i^rass may carry the amount all th(! way fr<im 
(he drops, too lie;i\y lo be retained upon llie blades, ihroiigh 
ihe thick adlM-ring films, to those which be<'oine invisible 
and are called hygroscopic. 

207. Observed Absorption of Moisture from the Air. 'jhe 
rate and amount (d moisliire which may be al)Sorbe(| iVoni 
the air is inlliieiicecl by many factors. ifilgard has studied 
the rate and amount of absorpi ion of moisture by soils when 
spread out in layei's about 1 m. m. thick in a fidly satural;ed 
and a lial I" s;il.iir;ited atmosphere, iiiainfained at a uniform 
temperal lire. lie (iiids thai, fully V hours ai'c re(piired 
for an e(piilibrinm to be reached in so thin a layei'. \n 
ihc table which lollows are iiiv'cn some of his observations. 



ITS 



Table ftfioirin;/ (fir al>Horpfivc poiri r of ,so/7.s spread out in thin 

lai/ers. 



KiM) OK Soil. 



Dark nlliivial loam, Piitali 
Valloy, Solano county... 



Satubated Atmosphbre. 



Tomp. 
Far.*' 



I 58 

I 59 

I 61 

I 77 

I 88 

I 100 



Time, 
lirs. 



Per cent, 
of water 
absorbed. 



11.745 

ii.s-^e 
ii,4as 
i2.oi;i 

12.23;< 
13.141 

ia.48i 



Half Saturated 
Atmosphere. 



Temp. 
Far." 



57 



70 

77 

88 

100 



Time, 
hrs. 



Per cent, 
of water 
ab.sorbed 



6 547 



6.424 
6.305 
().3.'i6 
6.209 



Black adobe soil, Univer- 
sity Kronnds, Alameda 
county 



Calcareous silt soil, Fresno 
county 



55 
57 
70 

80.5 
82.5 
100 



19 
19 

7 
17 

7.5 

7 



7.144 

7. two 
7.696 
8.681 
8.948 
9.569 



61 


18 


61 


7 5 


80 


6 


83 


7.5 


89.5 


7.5 


100 


7 



2.133 
2,983 
3.396 
4.211 



59 


18 


79 


6 


84 


7 


95 


6 



4.008 
4 122 
4.024 
3.926 
3.910 
3.885 



0.987 
0.959 
0.858 
0.821 



It will be soon that in the sntiirattMl atmosplun-o the 
largest amount of nKnstnve was absorbed at the highest 
temperature, while the rtncrse was true in the half sat- 
nratetl atmos})hert'. I'nder the high tem]ierature the rate 
of moleeular movcuu'ut is so ra]ii(l that tlu> rate at whieh 
the watiM' troiu ihc air falls upon autl enters llu> soil is so 
mueh iuereascd that nitirc water must have aeeumnlated 
in the soil hetori' the nnniher ef nidlecnles whieh can 
leave its surfaee in a unit of time equals that whieh falls 
upon it. Tn the drver atmosphere, on the other hand. 
Avhere there iwo less moliH'ules to fall npiui tlu^ soil and 
iner(\ise its aniouuf, the liigher teuiperaturi' favors ihe 
rajtid es('n|)e as nuu-h as when the saturation was high 
and, siuee less water is eondensing, a lower ptn* cent, is 
finally present when an equilibrium of interehang-e hao 
been reached. 



17!> 

208. Internal Evaporation of Soil Moisture. — It is likely 
that uiK-lcr ccrtaiii c(tii(lil ions llic ihcniial movements of 
soil moisture may be considei-ahh^ and perliaps of sufficient 
imjxtrtance to materially inliueiice vegetation, directly or 
iniiiroctly. When tlu^ jkm- cent, of imoceupied pore space 
in a soil has been materially increased by the loss of wa- 
ter and when the moistuni films have become so thin that 
capillarity is much enfeebled it is possible that internal 
evaporation of soil moisture may result in a considerable 
change of its ]iosition. If, for (wample, when the soil has 
become quite dry, to considci-ablc depths, the surface six 
inches should become cooler than that below, the tendency 
to continual difl"usi<iii of waler vapor under the impulse 
of heat would ju-oduce more iiitei-nal evajjoration of moist- 
ure where the soil is warmesi and most m(jist, and a larger 
condensation of inoisliirc wlicre I he soil is dryer and cool- 
er. Even where; there is little ditfei-enc^e in temperature be- 
tween adjacent layers of soil there must be, if they are not 
equally saturated, a teiidciicy toi- diffusion to take place 
more rapidly from the wcttesl. layer of soil toward that 
which is least moist. it is possible that dui-iiig di'v times 
and in dry clinuites dui'ing the dry season some moisture, 
too far below tlu^ root zone to be made available thi'ough 
ca])illarity, may be cai-ricMl iipwai'd by these thei'iiial or 
eva])oration movements so as to become helj)ful io ero])S in 
a measure. We are yet lacking in ex))ei-imental data to 
form any just eoneeplioii as to the iiiagiiit iide of snch a 
movement. 

209. Temperature Influence of Hygroscopic Moisture. — Tt 

is Ililgard's view that, in dry cdinuites and dnring droughty 
periods in humid climates, the moisture still retained by 
soils when capillarity has become very f(H'ble nniy exert 
an important influence in preventing the soil from becom- 
ing overheated during dry soil conditions, by the cooling 
effect of internal evaporation. It must be observed, how- 
ever, that in order that this inflnen(!e may become effective 
the moisture evapoi-at(MJ must lia\'e left the soil and not 



ISO 

have been replaced by an equal amount tlirougli condensa- 
tion from some other place. 

It appears to the writer possible that the ability of such 
soils to withstand drougiit may perhaps bo partly due to 
a more rapid evaporation from the soil grains and con- 
densation of moisture on the root hairs, the thermal move- 
ment, in this way, tending to supplement the enfeebled 
capillarity. 



181 



CHAPTER VI II. 

CONSERVATION OF SOIL MOISTURE. 

There are very few fields upon wliieli crops of any kind, 
in any climate, can be brought to maturity with the max- 
imum yields tlie soils are capable of producing without 
adopting means of saving the soil moisture. There are 
fields,, it is true, where, at times, the moisture in the soil 
is too great, and drainage becomes necessary ; but even un- 
der these conditions it will usually be found advisable to 
adopt measures for conserving the water not so removed. 

210. Modes of Controlling Soil Moisture. — In aiming to. 
control soil moisture three distinct lines of operation are 
followed, based upon as many different aims. These are: 

(1) To conserve the moisture already in the soil (a) 
by different modes, times and frequencies of tillage, (b) 
by the ap]dication of mulches, and (c) by establishing 
wind breaks. 

(2) To reduce the (juantity of water in a soil (a) by 
frequent stirring, (b) by ridging or firming the surface, 
(c) by decreasing the water capacity, and (d) by surface 
or under drainage. 

(3) To increase the amount of water in a soil (a) by 
increasing its water capacity, (b) by strengthening the 
ca])illarv movomciit u])ward and (c) by irrigation. 

211. Late Fall Plowing to Conserve Moisture. — There is 
no method of develo}>ing so effective a soil mulch as that 
furnished by a tool which, like the plow, completely cuts 
off a layer of surface soil and returns it loosely, bottom 
up, to place again. 

11 



182 

AVIr'u grouiKl is plowed late in the fall, just before 
freezing, it then acts during the winter and early spring 
as a niuleh, diminishing the loss of water by surface evapo- 
ration, and at the same time the roughened surface tends 
to hold the snows and to permit winter and early spring 
rains to penetrate more deeply into the soil, leaving the 
ground more moist at seeding time than would be the case 
if it were left unplowed. Determinations of the moisture 
in the spring, as late as May 14, have proved that late fall 
plowed ground may contain fully 6 pounds per square foot 
more water in the upper four feet than similar adja- 
cent ground not plowed. This diifereuce represents a 
rainfall of 1.15 inches and is a very important saving in 
climates of deficient water sui>])ly for crops. 

212. Late Tillage for Orchards and Small Fruits. — Late 
fall plowing and deep cultivation in orchards of fruit 
trees and in vineyards of small fruits, after the wood is 
fully matured and growth arrested by the cold weather, 
will do very much toward giving the soil better moisture 
relations the next spring, tending to secure such results 
as are cited in (211). In cases where injury from deep 
freezing is liable to occur the late plowing will lessen this 
danger because the loose soil blanket will help to retain 
the heat in the ground as well as the soil moisture. 

In the late plowing and deep tillage, advised in this and 
the last section, there is little danger of increasing the loss 
of plant food by leaching because the season is too late 
and the temperature of the soil too low to stimulate the 
formation of nitrates. 

213. Early Fall Plowing- to Save Soil Moisture. — lu those 
cases where winter grain is to be sowed, the early plowing 
of the ground, or plowing as soon as the field has been 
freed from the preceding crop, is in the direction of econ- 
omy of soil moisture. So too in sub-humid climates, even 
Avhere winter grain is not to be sowed, it will often be 
desirable to plow as early as possible in order to retain 



183 

soil moisture and to facilitate the entrance of the fall rains 
more deeply into the ground. The early plowing or disk- 
ing in these cases may also be helpful in hastening nitrifi- 
cation in the soil. 

It is the strong tendency of early fall plowing, in cli- 
mates where there is plenty of soil moisture tx) develop 
nitrates and where there is much rain in the late fall and 
early spring, wliich has led to the sowing of "cover crops" 
having tVjr their primarv object the locking up of the solu- 
ble plant foods to prevent them from being lost by soil 
leaching; and the tendency of early fall plowing to dimin- 
ish surface evaporation and thus, in wet climates, to in- 
crease jiercolation and the loss of plant food may some- 
times make this practice undc^sirable in such cases. 

214. Early Spring Plowing to Save Soil Moisture. — In all 
climates where there is a tendency of the soil to become 
too dry the earliest stirring in the spring, which is prac- 
ticable without injuring the soil texture, is in the direc- 
tion of economy in most cases because, at this season of the 
year, the effectiveness of tillage in conserving soil moisture 
is greater than at almost any other time. This statement 
follows from (198), wdiere it is shown that a wet soil car- 
ries water to the surface much more rapidly and from a 
greater depth than a dry soil can. In the spring the soil 
at the surface is usually not only wet but also well com- 
pacted, two of tlie most important conditions for the rapid 
movement of water to the surface, and it is because of 
these that early and deep spring tillage is so important 
as a means of saving soil moisture. 

In one instance, where two immediately adjacent pieces 
of ground, in every way alike, were plowed in the spring, 
7 days apart, it was found that the earliest plowed ground 
contained, at the time the second piece was plowed, a lit- 
tle more moisture in the uppep four feet than it had 7 days 
before, while the ground which had not been plowed had 
lost, in the same interval of time, an amount of moisture 
from the surface four feet equal to 1.75 inches, a full 



184 




185 

C'ii!,-lith <»L' till' rainfall of llic i;r<)\viii^' .season of tliiit lo- 
cality. 

JSTorvvastlio saviiii>; of inoistiiro the only advantaiiv ii'ained 
by the early plowing, for the soil plowed last had dried so 
extensively as to become very hard and lumpy, thus great- 
ly increasing the labor necossai-y to fit it for planting. 

In another rxpci'iincnt to slndy tiu^ effectiven(!ss of 
carl\- as coinpai-cMl with late sjn'ing ])lowiiig in conserving 
soil nioisture Fig. 57 shows how eN'ideiit the eti'ects were 
to the eye. 

215. Disking- or Harrowing Where There is Not Time to 
Plow. — It often happens in the H])ring that hot dvy winds 
come on when there is not o])])ortnnity to get the ground 
plowed in time to save the needed nioistnre and ])i-event 
the develoi)nient of clods. In such (;ases the use of tlio 
disk harrow, or even the ordinary s]dke tooth harrow, will 
do vei'v nmeh to save iho moisture and ])reserve tlie tilth 
of the soil, if oidy the fields are gone over with these. The 
disk harrow is one of the best of tools for early nse in 
the spring to work the soil and de\'elo]) mulches. 

216. Corn and Potato Ground, Orchards and Gardens 
Plowed Early in the Spring. — (iroiind to be ])lanted to corn 
or ])otat.oes, as well as the orchard and gai'den, should gen- 
erally bo plowed (piite eai'ly in the spring and a consid- 
erable time before it is intended to plant them. By doing 
this, not only will moisture be saved but the development 
of nitrates in the soil will b(> hastened and thus larger 
crops secured on this account. It is only in the event of 
long, frequent and heavy rains, following such early tillage, 
that loss can result from such a ])i'actice. 

217. Effectiveness of Soil Mulches. — I'lie effectiveness of 
soil mulches as means for diminishing evaporation variea 
(1) with the size of the soil grains, (2) with the coarse- 
ness of the crumb structure, (3) with the thickness of the 
mulch and (4) with the frequency witli which the soil is 



186 



stirred. Soils which maintain a strong capiRary rise of 
water throngh them will, when converted into mnlches^ 
still permit the water to waste through their mulches faster 
than it will be lost through the mulches of soils which 
permit only slow capillary movements. That is, the sandy 
soils for more effective mulches than do the clayey ones 
and this greater effectiveness of the sandy soils, as mulches, 
goes a long way toward making the smaller amount of 
w^ater they are able to retain effective in crop production. 
In Fig. 58 is show^n an apparatus for measuring the 
relative effectiveness of mulches and in the table which 
follows are given the results of a series of trials with 
three types of soil. The cylinders in this series, however, 
stood out in the open air of the field rather than in the 
case shown in the cut. 



Table showing the effectiveness of soil mulches of different 
kinds and different thicknesses. 





No mulch, 

water lost 

per 100 

days. 


Mulch 
1 in. deep, 
water lost 

per 100 
days. 


Mulch 
2 in. deep, 
water lost 

per 100 

days. 


Mulch 
3 in. deep, 
water lost 

per 100 

days. 


Mulch 
4 in. deep, 
water lost 

per 100 
days. 


Black marsh soil : 


588.0 
5.193 


355.0 
3.12 

39.54 


270.0 
2.384 

54.08 


256.4 
2.265 

56.39 


252 5 


Inches of water 
Per cent, saved 


by 


2.230 
57.06 








Sandy loam : 


741.5 

6.548 


373.7 
3.300 

49.69 


339.3 
2.996 

54 24 


287.5 
2.539 

61.22 


315.4 


Inches of water . 
Per cent, saved 


by 


2.785 
57.47 








Virgin clay loam : 
Tons per acre . . . 
inches of water . 
Per cent, saved 


by 


2,414. 
21.31 


1.260. 
11.13 

47.76 


979.7 
8.652 

59.38 


889.2 

7.852 

63.13 


883.9 
7.805 

63.34 









From this table it will be seen that the soil mulches have 
exerted a very great influence in saving soil moisture. 



187 



It should be understood, however, that if the water 
reservoirs had been much farther below the surface of the 
soil, and below the mulch, the mulches would have been 
more effective as w^ell as less water would have been lost 
from the unmulched cylinders. 

218. Frequency of Cultivation May Make Mulches More 
Effective. — When a fresh mulch is formed upon the surface 
of a well moistened soil the first eifect of the stirring; is 



iH 



Ji 



ii 



lh 




Fig. 58.— Ai)paratii.-; fcv measui-iiig- the relative efl'er-ti^'eness of mulches. 



to increase the rate of evaporation from the field, on ac- 
count of the much larger surface of wet soil w^hich is ex- 
posed to the air. This gi'eater loss of water, however, is 
largely from the stirred soil. If dry wdnds and sunny 
weather follow the formation of the soil mulch it soon 
becomes so dry that but a relatively small amount of wa- 
ter can pass up through it. On the other hand if a series 
of cloudy days follow, when the rate of evaporation 
must be small even from firm wet soil, and if at the same 
time the soil below the mulch is quite moist, so much water 
may pass up into the mulch as to nearly saturate the 
lower portion of it and to cause the kernels to be drawn 



188 



togX't.lici- iiiiil iiiiiiin ('()m|.;iclc(l .'iiid I'cmiilcd willi llic im- 

stirnid soil Ix'low. IT this clinii^c diH'^ l;ikc |t|;ic(' tlic 

inulcrli is rendered less (dlecliv*' iiiid ;i second slirriiij;' is 
iieediMJ. 




li'h!. U'.l Slidwin.; |;ir.<;<> cy liiidci-s I'lir si iid \ i iii;' s,iil prdlili'ius. 



'rile rel;ili\-e elleel iveiiess of innlclies stirred Iwiee per 
\veek, once |)er wi'ek. jind once in I wo weeks, foi' a virgin 
<'lav loam, in c\lind('rs 52 Indies dee|) and IS inclios in 
<lianieler, staiidini;- in our jilanl. lionse, as sliown in I*'iii". 
5'.*, is iii\-en in the tahle wliicli follows. 



,H1> 



Table Hlioirino the relative effect Iveiienn of noil tnalcheH of <lif- 
ferenl dept/m and (lijfirent fre<fueiieieH of r.ullivation. 





Not culti- 

vatod. 
Por ucrci. 

724.1 
6,394 


Onco in 

2 wookH. 
Por ucro. 


Onco per 

W(tOK. 

Por ucro. 


Twice per 

WO(tK. 

Por aero. 


Cultivated ono incli doojp : ' 
Tlio loHH in tons porlOOdayH wuk 
'f li<i losH in inclioH por 100 dnyx 


551.2 

4.867 
23.88 


545.0 
4.812 
24.73 


527.8 
4.662 


Tho ijerceutago of wator uaved 
was 


27.10 









(Jtiltival(Ml two iiiclio.M doop: 
'i'lio lo.-^H in tons p(w KXJ dajH wa.s 
Tlin los.s in mclioH i«)r lou dayti 


724,1 
6.394 


609.2 
5.380 
15.88 


552.1 

4 87.') 
23.76 


515.4 
4.. 5.52 


Tlio porcontago of wator Huvod 


28.81 








Cultivated tlinni iiiclios dooj): 
'I'liD lo.ss in toiiH por 100 (luy.s wa.s 
Tlio lo.s.s in inclioH por 100 dayH 

was 

Tlio imrcontaxe of water saved 


724.1 
6.391 


612.0 
5,280 
15,49 


531 5 

4.694 
26 <» 


4X).0 

4 371 
31.64 









It will l)(! .sooii thill, with ciH'h ol' th(; three (lcj)lhs ol" cul- 
tivation th(! |)(!rccnt,a^c ol' iiioistiirc waved, ovc.v t.hat, wliich 
was lo.st, from the ground not (!iilt,ivate(l, iiicreastid willi tho 

ri'e(|iiciicv (d' eull i\al ioli. 

219. Too Frequent Cultivation Undesirable. When a .soil 
nnijeh i-; well looseneil ;iiid 1 liofonfi,hl_y s(i])arat(!(l froiri the 
hi-Mi i^roiind heiiealli, and especially after tho imil(!li lias 
liei'uiiie (|iiile dry, lit/th^ can he gained l)y stirrin;^- the .soil. 
Jndeed it, iiiiisl ever l)f! ke|)t, in mind that it costs to cul- 
tivate a field and when this is done without ii(K;d the work 
is a dead loss. I''iirt her than this, late in t,he season, when 
the surface of the ground has hecome relatively dry, posi- 
tive iiann may he done \)\ iinnecessary enltivation b(!caiise 
at, tliis Hea.son many |)laiits have put up, very close tf) 
tlici surface, j^roat niimhers of line roots in order to 
avail thcnnselvrss of the moisture from jio-ht sliowcrs and 
from the dew which may lie condensed in the surface layer 



190 

of soil (111 the coolest nights. To destroy these roots will, 
in most cases, cause a greater loss by root pruning' than 
can be gained by saving nioistnre. It is possible also, by 
too frequent tillage, to make the textiire of the mulch so 
fine that its effectiveness is decreased. 

220. Cultivations Should Be Most Frequent in the Spring. 

In the early part of the season when the aeration of the 
soil, the warming of it and the killing of weeds are other 
imjiortant objects to he attained it is more important to 
cultivate frequently. This is the season of the year when 
the effectiveness of mulches decreases most rapidly, it is 
the season when there is least danger of destroying the 
roots of the cro]), and it is the time when cultivation is 
needed to hclj) (h'velo]) })huit food. 

221. Cultivation After Heavy Rains. — Whenever a rain 
has occurred which has thoroughly united the soil crumbs 
to one another, and with the soil below, it is time to cul- 
tivate again if this can possibly be done without too heavy 
root pruning, and the cultivation should be done just as 
quickly as the soil will permit. In the early part of the 
season there is little danger of root pruning if the culti- 
vator teeth do not go too close to tlu^ ])lants and not more 
than 3 inches deep. 

A rain which does not wet down more than o inches 
cannot be saved by cultivation ; all that can be done in 
this case is to permit the surface roots to get as much 
of it as possible and to stir, if it ap]iears expedient, when 
the wetting is likely to strengthen the upward movement 
too much. It must be remembered in this connection, 
however, that if, late in the season, the roots of the crop 
have spread horizontally through the whole soil, anything 
which strengthens the rise of the deeper water, causing 
it to come nearer the surface, at the same time brings it 
to the roots where it is needed, and hence it will seldom 
hajipen that a crop like corn or potatoes can be helped by 



l!»l 

cultivation after the corn is in tassel or the vines begin to 
well cover the ground. 

222. Depth of Cultivation to Save Moisture. — In regard 

to tiiis point it must hv kept in mind that tlie soils out of 
which mulches are made are the richest on the farm and that 
when they are converted into perfect mulches they are prac- 
tically useless so far as direct plant feeding is concerned. 
The general rule must then be to make the mulch just 
as thin as it can be and not permit too heavy a waste of 
the deeper soil water. 

On the lighter and coarser grained soils the mulches 
may be shallower than on those of the clayey type. 

in Wisconsin we have found that with the ordinary 
narrow j}ointed tooth cultivators a depth of about three 
inches saves more moisture and permits larger yields of 
corn in about 15 cases out of 20 than less depth of culti- 
vation. Where the tool is of such a character that it 
shaves oif the whole surface of the ground and leaves the 
stirred soil spread in a blanket of uniform thickness the 
stirring nmy be shallower than if the surface of the ground 
is left in cither narrow or wide ridges. 

223. Depth and Frequency of Cultivation Should Vary 
With the Season and Crop. — From what has been said in the 
preceding paragra[)lis it follows that the soil may to ad- 
vantage be cultivated more deeply and more frequently 
during the early part of the season when the soil tem- 
peratures tend to be low, when the moisture may be over- 
abundant, and when weed seeds are germinating. Later 
in the season, however, when there is not as great need 
to encourage the development of nitrates by tillage, when 
the roots have come closer to the surface, and the main- 
tenance of a soil mulch is the chief or only object, the 
cultivation may evidently be less deep and not so fre- 
quent. The general practice then should be to gradually 
make the cultivation both less deep and less frequent. It 
should also be kept in mind that cultivation may gener- 



1D2 

ally be a little deeper in the middle of the space between 
rows, than close to the hills, because of less danger of root 
pruning. 

224. Best Time to Cultivate Corn and Potatoes. — The best 
time to till land for corn, potatoes and similar crops, where 
int^rtillage is practiced, is before the gronnd. is planted 
and just as the crop is coming np. When the gronnd is 
plowed two or three weeks before the crop is to be planted 
there is opportunity to develop the nitrates, to kill one 
or two crops of weeds, and to store in the up2>er five feet 
of soil the largest reserve of soil moisture from the spring 
rains. Besides these advantages there is no period in 
the growth of the crop when the ground can be stirred so 
rapidly and so cheaply. Before planting the disk or 
spring-tooth harrow may be used and afterward the dif- 
ferent weights of spike-tooth harrows, which enable a 
larger area of ground to be covered in a day by a man 
and team. The harrowing of corn and potatoes should 
be continued until the plants are well out of the ground 
and if care is taken to do the work during the hot por- 
tion of the day, when from slight Avilting the plants do 
not break off readily, there need be but little serious in- 
jury to them. 

The different types of mulch producing tools are dis- 
cussed in the chapter on Implements of Tillage. 

225. Harrowing and Rolling Small Grain After It Is Up. — 

It sometimes happens in hunlid climates, when drying 
weather follows a wet period, that a crust forms on the 
surface of fields sowed to the small grains, which may 
be injurious to the plants by preventing sufficient aera- 
tion and increasing the loss of moisture. In such cases 
the difficulties may be partly corrected by using either the 
roller or the light harrow with teeth sloping backward. 

If the grain is large, and especially if the surface of 
the field has been left narrowly ridged and somewhat 
lumpy, the use of the roller irhen the surface soil is dry 



193 

will break up the crust by crumbling down the ridges and 
lumps and at the same time develop a true and eliective 
mulch. The light harrow, when driven across the ridges, 
may be effective in breaking up the crust and in develop- 
ing a mulch. 

In sub-humid climates, such as that of western Ivansas, 
fields seeded permanently to alfalfa have been, in the 
very early spring, gone over with the disk harrow and 
then crossed with the spike-tooth harrow, thus developing 
a very effective mulch which materially increases the yield. 

226. Mulches Not Made From Soil. — While it is true that 
most conservation of moisture must be through earth 
mulches it should be understood that all vegetation growing 
upon the ground, whether it completely covers the surface 
or not, exerts a protective influence and diminishes the 
loss of moisture directly from the soil itself. This pro- 
tection comes partly from shading, partly from diminish- 
ing the wind velocity and partly from the saturation of 
the air with moisture by the transpiration from the grow- 
ing plants. 

Even in pastures where the grass is short, but close, the 
mulching effect is strong and hence it is not in the direc- 
tion of economy to allow the feeding to be too close, not 
only because the growth of the grass is slower from too 
severe destruction of the foliage, but because there is a 
greater loss of soil moisture besides that passing through 
the grass. 

The surface dressing of meadows with farmyard manure, 
thoroughly harrowed to spread it evenly over the ground, 
is extremely beneficial through its mulching effect as well 
as in the plant food it brings to the soil. When such 
dressings are applied in the winter and early spring and 
spread over the surface while the soil is yet wet beneath, 
the saving in soil moisture is greatest and in the case of 
meadows where the clover has disappeared, for any rea- 
son, such a dressing may make it possible to get a new 
seeding, by sowing the clover broadcast before the frost 



194 

is out in the spring, so that the thawing and freezing will 
tend to cover the seed and the thin mulch protect the 
ground from too rapid drying until the young plants are 
well rooted. 

The use of straw and other coarse litter and coarse sand 
for mulching will generally only be practicable in gardens 
and orchards and for the protection of shade trees and 
the like. 

227. Ridged and Flat Cultivation. — It used to be a com- 
mon practice to "lay by" the corn and potato crop wath 
a strong hilling of the rows. This practice, however, ex- 
cept for potatoes, is now generally abandoned unless in 
localities where surface drainage is needed. The general 
abandonment of the j)ractice rests in part u]>on the be- 
lief that the evaporation from the soil is appreciably in- 
creased by this process on account of the greater amount 
of surface exposed to the air. 

In making a practical test during the season of 1899 
the results recorded in the following table were secured. 

These plots, each seven rows wide, alternated across a 
field of nearly uniform soil and samples were taken under 
and between every row. It will be seen that the soil re- 
ceiving the flat cultivation contained at the end of the 
growing season a little less water than the ridged plots, 
which is contrary to the accepted belief. Since the ridges 
are all shaded by the potato vines and since the wind cur- 
rents may be supposed to be less strong betweeii Jhe fur- 
rows, perhaps this is as should be expected. It is true, 
however, that the plots cultivated flat produced a little 
larger yield per acre and on this account the soil should 
have lost more moisture. It may be that the flat cul- 
tivation did really make a larger saving of water and that 
this savinc: was the cause of the larger vield. 



195 



Table showing the water content of soil, Sept. 19, wider and 
between roivs of potatoes hilled and left fiat when laid by. 





Nos. of 
sub- 
plots. 


Hilled, 


Flat, 


Depth of S.\mple. 


In row. 


Between 
row. 


In row. 


Between 
row. 


( 


1 


Per cent, 
12.8a 
12.01 


Per cent. 
14.11 
13.61 


Per cent, 
11.85 
12.18 


Per cent. 
14.23 


First foot \ 


2 


13.54 




3 




Mean 

1 




13.86 








12.42 


12.02 


13.89 


i 


16.71 
15.84 


18.56 

17.85 


15.38 
16.03 


17.69 




2 


17.84 




3 




Mean — 
1 












16.28 


18.21 


15.71 


17.77 


( 


18,00 
17.09 


18.61 
17.55 


16.41 
16.13 


18.03 


Third foot K 


2 


17.97 




3 






Mean 

1 






16.27 






17.55 


18.08 


18.00 


( 


15.78 
14.41 


16.95 
13.98 


9.79 
13.08 


11.75 


Fourth foot . . . . ■< 


2 


14.01 




3 






Mean 






11.44 

13.86 






15.06 
15.33 


15.46 

16.40 


12.88 
15.64 









228. Subsoiling to Save Soil Moisture. — The deep plowing 
or stirring of the soil, to which this name has been applied, 
has the effect of making a larger per cent, of the rainfall 
available in producing crops, but it will never have the 
wide applicability that is possible for surface tillage. In 
sub-humid climates where the subsoils are less liable to be 
puddled and where there is the greatest need of economy 
this method of conserving soil moisture will find its widest 
usefulness. 

A piece of ground when subsoiled, as represented in 
Fig. 60 and given, with an adjacent area, a like amount 
of water, and protected from surface evaporation, was 
found to have retained not only the water given it but to 
have gained an additional supply through capillarity from 
below; while the ground not subsoiled lost a large per 
cent, of that given to it through percolation and capillary 



10 G 



creeping. From the siibsoilod area 8 inches of the surface 
:\vere removed, the snbsoil spaded to a dejjth of 13 inches 
more, and the soil returned to its place. After taking 

ntV\' 









samples from ihc live plaees indicated by the dots, 1.36 
inches of water were gradually sprinkled over the two 
areas on June 11th and they -were allowed to remain cov- 
ered until the IStli, wdien samples were again taken. The 
changes in the water content of the soil in the two areas 
are shown in the table which follows: 



Table showing the ability of nubsoilcd ground to hold water 
against gravity. 





Snbsoiled. 


Not 
subsoiled. 


Difference. 


Tlie first foot trained 


Lbs. 

124.6 

72.. 57 

.•W.22 

33.26 

2.29 

268.65 
254.41 


Lbs. 

102.1 
10 34 
12.05 
3.82 
19.5 


Lbs. 

+22.5 
4 62.23 
426.17 
+29.43 
17 21 


Tlio s(>coiid foot paiiKid 

Tlie third foot Rained 


Tho fourth foot pained 

The fifth foot lost 






Total water gained 


128.31 
254.41 




Total water added 








Difference 


+14.24 


—126.1 









197 

The subsoiled gTOund had therefore not only retained 
all the water added but it had gained by capillarity 14.24: 
lbs. more. It is noteworthy too that the fifth foot in both 
23laces had lost water upward by capillarity, 2.29 lbs. in 
the former and 19.5 lbs. in the latter case. 

The effect of subsoiling on the capillary rise of water 
from below was demonstrated by using the same piece of 
apparatus in the same way except that the two areas were 
<3overed to prevent evaporation, without adding any water, 
the experiment extending from June 26 until July 2, giv- 
ing the results shown in the next table. 



Table showing the effect of subsoiling on the capillary rise of 
ivater from the deeper soil when no evaporation can take 
place from the surface. 



J"-26 j^?^] 

'^y^ \^^^1^Z\ 

Change 

June 26— start 

July 2— close 

Change 



22.52 
23.97 



+1.45 



On Subsoiled Ground. 



1st foot. 


2ad foot. 


3rd foot. 


4th foot. 


5th foot. 


Per ct. 
23.29 

22.66 


Per ct. 

21.89 

22.50 


Per ct. 

17.85 

17.49 


Per ct. 
14.14 

14.45 


Per ct. 
19.55 

20.27 


- .63 


+ .61 


- .36 


+ .31 


+ .72 


On Ground not Subsoiled. 



20.67 
22.09 



+1.32 



17.74 
18.92 



+1.18 



15.06 
14 62 



.44 



19.34 
18.33 



It will be seen that in the subsoiled area there had been 
but little change in the water condition while the ground 
not subsoiled had gained a very material amount of water 
in the surface three feet at the expense of that deeper in 
the ground, the gain in the upper three feet amounting, 
on the 36 square feet, to 129.69 lbs., 53.52 lbs. having 
come from the fourth and fifth feet and the balance prob- 
ably partly from the sides and partly from the sixth foot. 

When the ground was subsoiled in the same manner as 
12 



198 



before and allowed to stand exposed under natural condi- 
tions, and the surface kept free from weeds by shaving 
them off close to the surface with a sharp hoe, it was fonnd^ 
after an interval of 75 days from June until September, 
that the water content of the soil stood as in the next table. 





Subsoiled 
ground. 


Not subsoiled 
ground. 


Difference. 




Per cent. 

17.07 
23.29 
22.76 
16.35 
18.14 


Per cent. 

18.91 
19.42 

17.78 
14.19 
19.20 


Per cent. 
—1.84 




+3.87 


Third foot 


+4.98 




+2.16 


Fifth foot 


—1.06 







In this case the surface foot of subsoiled gi-ound is dryer 
than that not so treated, but the second, third and fourth 
have gained in moisture, over and above that lost from the 
other two feet, enough to represent a rainfall of 1.64 
inches. 

229. Moisture Effects of Subsoiling. — The results whick 
have been given in the last section illustrate several very 
distinct effects produced by subsoiling: 

(1) Subsoiling increases the jjercentage capacity of the 
soils stirred for moisture. 

(.2) Subsoiling decreases the capillary conducting power 
of the soil stirred. 

(3) Subsoiling increases percolation through the soil 
stirred or its gravitational conducting capacity. 

230. How Subsoiling Increases the Water Capacity of the 
Soil Stirred. — When a soil is broken into lumps lying loosely 
together, and these become filled with water, each one 
behaves in a measure much as if it were standing by it- 
self and much as a lump of sugar Avould, plunged into 
water and then withdrawn, coming forth with its pores 
practically filled with water. In short columns of soil, 
like the lumps, the surface films of water which span their 
capillary pores are strong enough to maintain their whole 



199 

interior nearly full of water, drainage being largely con- 
fined to those passageways and cavities which have larger 
than capillary dimensions. 

If a dozen strands of candle-wicking, two feet long, are 
twisted loosely together, saturated in a basin of water, and 
then held horizontally from the two ends to drain, more 
water will be retained than if it is allowed to sag into a 
loop and drainage from it will be still more complete when 
hanging from one end. So it is with long continuous col- 
umns of soil ; from them the drainage is more complete 
than from shorter ones. 

231. How Subsoiling Decreases the Capillary Conducting 
Power. — When large open spaces have been formed in a 
soil, by any means, las is the case in subsoiling, every such 
cavity cuts off the capillary connection with the unstirred 
soil below and above and in this way reduces the number 
of capillary passageways by which water may rise to the 
surface. This being true, when rains fall upon subsoiled 
ground, water travels downward quite slowly until after it 
has become capillarily saturated and, if the rain is not 
enough to over-saturate the layer, the whole will be retained. 

On the other hand, when the subsoiled layer has once 
become dry, the poor connection with the firmer ground 
below and its open texture makes it impossible for the 
moisture to rise through it to the surface as rapidly as it 
could through a more compact layer. 

It is clear, from these relations, that when the root 
system of a crop once develops through the subsoiled layer 
it may then act as a mulch of great thickness and increase 
the yield ; but should a crop fail to get its roots below the 
subsoiled layer before the moisture becomes too scanty 
then a diminished yield might be the result even with an 
abundance of water below. 

232. How Subsoiling Favors Percolation. — When rain 
enough has fallen upon an earth mulch or upon subsoiled 
ground to completely saturate the soil the balance of tha 



200 

water is tlien free to move rapidly dowiiAvard through tho 
large n-on-capinary pores, urged by the strong force of 
gravity. ]^ot only this, bnt, since the pores are many of 
them too large to be filled by the percolating streams, there 
is left an easy egress for the soil-air, which must escape 
upward before the M^ater can enter, and this does not re- 
tard percolation as it does in a compact soil. 

233. A Larger Percentage of the Moisture of Subsoiled 
Ground Available to Crops. — When a soil has been made 
more open by subsoiling, and its capacity for holding water 
thereby increased, this extra amount of water retained be- 
comes wholly available to crops. It "svas shown in (161) 
and (162) that there is a certain ])er cent, of water in a 
soil which the roots of plants are unable to remove with 
sufficient rapidity to meet their needs and as this amount 
depends upon the size of the soil grains, which subsoiling 
does not alter, the increased percentage held becomes a 
clear gain to the crop. 

234. Dangers From Subsoiling. — One of the most serious 
difficulties associated with subsoiling, aside from the ex- 
pense, is the danger of puddling, and this is particularly 
great in humid climates wdiere the subsoil, especially in 
the spring, is liable to be too wet. The danger is intensi- 
fied on account of the fact that the surface soil may be 
in good condition for plowing when that below is much too 
wet. If this work is attempted when the ground is not in 
condition very great harm may be done and so it is gen- 
erally much safer to subsoil late in the fall in humid cli- 
mates, when the deeper ground is generally dryest. 

235. Early Seeding. — When the crop is started to grow- 
ing upon the ground as early as the temperature of the 
soil and of the air will permit the farmer is conserving soil 
m'oisture, by taking advantage of that which otherwise 
would be lost by surface evaporation, and enabling his crop 
to use this in growth. Such timely i)lanting may not only 



201 



save moisture from going to waste, both by evaporation 
and by percolation, but it may save plant food from loss 
in the drainage waters. 

Yet, while dno diligence should be exercised in timely 
planting and sowing, tliere is danger of too great haste and 
it will generally be better to make the mistake of getting 
the crop in a little late rather than too early. The soil 
should by all means be warm enough and dry enough to 
make germination prompt and vigorous, for otherwise weak 
and sickly plants will result, if the seed does not rot in 
the ground. 

236. Danger From Green Manuring. — In the practice of 
growing cover-crops, and in green manuring, attention 
must always be given to the effect these have upon the soil 
moisture, as related to the crop which is to follow. When 
either rye or clover is used in green manuring, and the 
plants are allowed to make a heavy growth before plowing 
under, the soil will be found very much dryer than if the 
field bad been plowed and tilled early but left naked, or 
even if not ])low('(l at all. The next table demonstrates 
the truth of this statement, showing, as it does, the strong 
drying effect of clover as early as May 13. 



Table ahoiv in cf the drying effect upon the soil of a green ma- 
nure crop. 





1 to 6 inches. 


12 to 18 inches. 


18 to 24 inches. 


Ground not planted 

Ground in clover 


Per cent. 

23.33 
9.59 

13.74 


Per cent. 

19.13 
14.75 


Per cent. 

16.85 
13.75 




4 38 


3 10 







In such a case as this, with the soil as dry when plowed 
as that under the clover, not only would there be danger 
of the seed not germinating properly but the large growth 
of herbage, when plowed under, would so much cut off 
the capillary connection with tlie deeper soil moisture that 



202 

it could not readily become available until after the roots 
had penetrated below this level. 

]^or is this all ; any snch cro]) would have locked up in 
insoluble form, for the time being, a large portion of the 
soluble plant food, and unless abundant and timely raina 
were to follow the ]»l()wing speedily to develop a new sup- 
ply, the next croj) would suffer for lack of nitrates and 
other plant foods. 

On soils naturally too wet and in wet seasons the dan- 
gers referred to will of course not be so great and the 
green manure crop might even be an advantage from the 
soil moisture side by making the over-wet soil more open, 
thus favoring stronger root action and more rapid nitri- 
fication. 

237. Wind-breaks and Hedges. — "Tu""'' sub-humid climates, 
especially like those of our western prairies, where there 
is a high mean wind velocity, and in the level districts 
of humid climates, where the soils are light and sandy, with 
a small water capacity, -Awd wiiich are lacking in adhesive 
quality, the fields nuiy suffer greatly at times, not only 
from excessive less of moisture, but the soil itself may be 
greatly danmged by drifting caused by the winds. Under 
such conditions, it is a matter of great importance that the 
wind velocities clos(^ to the surface should be reduced as 
much as possible." 

On the lighter saiuly lands, wherever broad fields lie 
unsheltered by any wind-break, strong dry winds frequent- 
ly sweep entirely away crops of grain after they are four 
inches high, and at the same time drift away even as much 
as three or four inches of the surface soil, the best in the 
field. In such cases wind-breaks and hedge-rows exert a 
very strong protective influence and greatly lessen such dis- 
astrous results. 

]^ot only do trees along line fences and roadsides, un- 
der these conditions, prevent such direct injuries to soil and 

* Irrigation and Drainage, p. 168. 



203 

<3rops l)ut they materially lessen the evaporation of moisture 
from the soil and thus help to secure a higher yield of 
crops. *''The A\TLter has observed that, when the rate of 
evaporation at 20, 40, and 60 feet to the leeward of a 
grove of black oak 15 to 20 feet high was 11.5 c. c, 11.6 
c. c, and 11.9 c. c, respectively, from a wet surface of 
27 square inches, it was 14.5, 14.2 and 14.7 c. c, at 280, 
300 and 320 feet distant, or 24 per cent, greater at the 
three outer stations than at the nearer ones. So, too, a 
scanty hedge-row produced observed differences in the rate 
of evaporation as follows, during an interval of one hour: 

At 20 feet from the hedge-row the evaporation was 10.3 c. c. 

At ISO feet from the hedge-row the evaporation was 12.5 c.c. 

At 300 feet from the hedge-row tlie evaporation was 13.4 c.c. 

Here the drying effect of the wind at 300 feet was 30 
per cent, greater than at 20 feet, and 7 per cent, greater 
than at 150 feet from the hedge. 

Then, too, when the air came across a clover field 780 
feet wide the observed rates of evaporation were : 

At 20 feet from clover 9.3c. c. 

At 150 feet from clover 12.1 c. c. 

At 300 feet from clover 13 c. c. 

Or 40 per cent, greater at 300 feet away than at 20 feet, 
and 7.4 per cent, greater than at 150 feet." 

* Irrigation and Drainage, p. 169. 



204 



CHAPTER IX. 
RELATION OF AIE TO SOIL. 

NEKDS OF SOIL VENTILATION. 

.Vir ill the soil in which crops are to be grown is as es- 
sential to tlic life (if the plants as the air in a stable is 
to the life of the animals honsed. 

Canvful observations and liiies of ex})eriiii(Mitation have 
proved, in many ways, that when oxygen is eoin})lctely ex- 
elnded from seeds that are otherwise nnder good conditions 
for germination they fail to start. It has been found, too, 
that even after a seed has begnn to grow, if the oxygen 
snpply is cnt off, it makes no farther progress. Growth 
does take place in seeds in a very dilnte atmosphere of oxy- 
gen, bnt aftcM- the amount has been reduced below sV of 
llie average in the air the jdants advance very slowly and 
are sickly. 

A soil in ilio best coiidilion for cro])s must permit of 
ready cut ranee: of fresh air and an abundant escape of 
the air once tis(h1 ; in other words, like the stable, it mnst 
be well ventilated. This ventilation is needed: 

(1) To supply free oxygen to be consumed in the soil. 

(2) To supply free nitrogen for the nse of the free- 
nitrogen-fixing germs. 

(3) To remove the excess of carl)on-dioxido which is 
set free in the soil. 

238. Needs For Free Oxygen in the Soil. — Free oxygen in 

the soil is recpiircd not only by the seeds, when they are 
germinating, but throughont the active life of the plant 
in order to permit the roots to live, for they, too, must 
breathe. 

Then in the conversion of the nitrogen of humus, manure, 



205 

and (.U'caviui:' orgiuiic iiuittcr in llic soil into iiiliMc acid, 
lai'C'e cUnounts of oxy^'cn arc ncc(|c(|, t'or cacli ol I lie three 
known forms of niicroscopic life wliieli '!<> this work are 
iniaMe to live in its absence. 

239. A Water-log-ged Soil. — One of tlu; chief reasons for 
the nnproUnctiveness of a water-h)iii>-e(l soil is the deficiency 
of free atniosphcric ox_vi>en in it. When the soil ]»ores are 
filled with water and this water is statitmarv, that is, not 
changinii', the free oxyiicn which it may contain in the air 
dissolved in it is soon nsed nj) and then the rate at which 
oxygen from the air almve the soil is able to make its way 
downwai-(l thi'onuli the soil-watei- and around and between 
the soil grains is mnch too slow to meet the <irdinary needs 
of the roots of any eroj). JSTot oidy this, hut, as pointed 
ont in (103), oven tlic microscopic organisms in the soil 
find so scanty a sni)ply that they are obliged to decompose 
the nitric acid for the oxygen it contains in order to supply 
their needs. The chief m^ed of draining wet lands, then, 
is to secure to the soil a more rapid change of air. 

240. Floating- Gardens. — T\w instances where the Chinese 
and .Mexicans grow cro]>s npon floating rafts of logs an- 
chored in a stream or lake and thinly covered with soil 
may seem to contradict the statenuMits in the last paragraph 
regarding a waterdogged soil because, in these cases, the 
soil is very wet in its lower portion and the roots of the 
]dants are continually immersed in a saturated soil or in 
the water itself beneath. A little reflection, however, will 
make it clear that the two cases are very different. Both 
in the lake and in the running stream the Avater is chang- 
ing continually so that a new sn|)ply, charged Avith fresh 
oxygen, is being continually brought- to the roots or very 
near them. 

It is the abundau'co of oxygen Avhich rain water and 
that nsed for irrigation contains which prevents it from 
killing crops when the water entering the soil is excessive. 
As long as the Avafer is moving thronuh the soil, and a 



20(3 

frcsli «u])ply from above cntei-iiig, an abundance of air 
is carried with it for the needs of the roots. 

241. Excessive Soil Ventilation. — Tlie higher temperature 
of a pile of open horse manure, as compared with tliat of 
the ch)ser lieap of cow-dung', ilhistrates how important the 
free and rapid access of air to the interior is to the forma- 
tion of the ammonia, for the difference in temperature in 
the two cases is largely due to a difference in the rate of 
fermentation, and this to the too rapid entrance of air. 
In these cases the air is entering too rapidly and a loss 
of nitrogen is the result. And the same thing may occur 
in a too open soil. Indeed, the small amount of humus in 
the sandy soils is in a large measui-c due to the freer ac- 
cess of air to the interior. 

It is for this reason that unusual care must be exercised 
to keep the supply of hunnis in these soils up, not only 
because of its need for plant food, but because it enables 
tlie sandy soils to hold more water, and this in turn makes 
them less readily ]ienetrated by the air and the humus does 
not waste as rapidly. 

242. Return of Carbon-Dioxide to the Air. — It is of course 
necessary to the continuance of ])lant life that the vast 
systems of roots which are develo]>ed in the soil should be 
broken down, first into humus and then into carbon-dioxide, 
water and free nitrogen, and all of tlie processes concerned 
in these changes demand free oxygen taken from the air 
and the escape of the carbon-dioxide and nitrogen gas set 
free, and here again is ample soil ventilation necessary. 

243. The Fixing of Free Nitrogen. — Tn the processes of 
symbiosis discussed in (101), Avhicli load to the removal of 
the free nitrogen of the air in the soil and soil moisture, 
and the conversion of it into organic compounds suitable 
for the food of higher plants, soil ventilation is necessary 
in order to suj^ply both the oxygen and nitrogen of the air 
which the micro-organisms are obliged to use in carrying on 
their life ]ux>cesses. 



207 



PROCESSES OF SOIL VENTILATI02C. 

Tlio interchange of gases between the soil and atmos- 
phere is brouglit about in several ways and by different 
agencies. Among these are (1) the slow process of diffu- 
sion described in (5) and (14). {'■2) The expansion and 
contraction of soil-air <lu(' to changes in temperature. (3) 
The expansion and compression of the air due to changes 
in barometric pressure. (4) The suctional effect of the 
wind, especially when it is gusty. (5) The air absorbed 
by rainwater is carried into the soil when percolation takes 
j)lace. (6) When water drains away from a soil or is 
carried upward and out by capillarity or root action it 
acts by suction to draw into the soil a volume of air equal 
to that of the water which ilows out. 

244. Ventilation of Soil by Diffusion. — The exchange of 
air between that in the soil and the atmosphere above by 
diffusion is a very slow process but, because it is all the 
time taking place, the total exchange during the growing 
season is considerable. The more open the texture of the 
soil is and the higher the soil temperature the more rap- 
idly will the intorehange l)y this process take place. 

245. Soil Ventilation Due to Changes in Soil Tempera- 
ture. — When the temperature of air is changed its volume 
is also altered and in the ratio of ^\>j for each degree 
F. or 57? for each degree C. ; so that if 4!>1 cubic feet 
of soil-air were to have its temperature changed 1° F. this 
would result in one cubic foot of air being forced out of 
the soil, if the t^^mperature was raised, and a like amount 
would enter if the temjH'ratni-e were to fall the same 
amount. 

The temperature of the surface three inches of soil often 
changes as much as 10° to 20° F. and that at 18 inches 
deep as much as 1.5° F. A soil like the surface foot in 
(133), coutaiiiiiig 1^ ]H'V cent, of water, would enclose 



i>()S 



:il»(Mit. .")..") iicrc-iiiclics of ;iir in llic siirlncc l.T) feel niid, 
willi ;i (liiininl clKiiiiic of 1(1.1 l'\ in llic ii]i|icr .'5 iiiclics 
iliid 1..') I'\ ;il ;i (|c|)lli of is inches, llir iinioiinl of soil-ilir 
M'liicli wonld lie forced onl :ind :ii;nin l;d<en in oacli 2-4 
]ioiii's wonld lie idiont 1 I cidiic inclics for cacli s(|nai'(' foot 
of ynrface. So llnil llic soil \-eiil ilal ion dnc to diuiMial 
('liaii_i>'('S in S(dl lenipcral nrc will rani;(' fr<ini iij> \o pos- 
sihlv I'O en. in. per s(|nare fool. 

246. Influences of Chang-es in Barometric Pressure on Soil 
Ventilation. — Anv <*haiif>'c wliicli luav occur in the prcs.sure 
(if the air al»(i\'e the soil is followed liv a (dniiiii'c in the 
Volnine of the soil-ail', cansini;- an escajie from the soil, if 
the pressnre aliii\-e falls, and ihe enli-ance of an extra snp- 
]ilv \\lieiie\'er the prcssni'e is inci'eascd. 

With soil like (hat in (133), liavinj;' IS |)or ccuf, of water 
in tho first foot, LM) per cent, in the second and 15 ]>er 
cent, in the third and fonrlli feel, there wonld he 7.8S 
inches in depth ol soihair containe(| in tli(> fonr fVet and 
ex'erv chanii'e in atmospheric pi'cssnre amonntinii" to .1 inch 
wonltl cause the escape oi- entrance of 3.TS cuhic inches 
J'or each s(piare foot of snrface and 18.0 cnhic inches for 
each clniniic in pi'cssnre of .."» inches of harometer. 

It is common in the Unitxnl States for waves of ]iiij:h 
and low jiressnre to pass a g'ivon locality ahont twice each 
wook, and the difFcronces in pressure hetween hiuh and low 
baronietei- ai-e ii'emM-ally not far from .Ti inch, so that the 
resnils s(ale<| aliox'e i;i\'e a J'air measni'e of this infinonce 
in soil \-ent.ilation. 

247. Wind Suction and Soil Ventilation. — Tt is seldom 
trne that the wind hlowini;- across a field has a nnifoi-ni 
velocity, the <i'eneral fendencv heinii' for it to hhnv in g-nsts. 
This nnstoady action tends at limes to inci-ease the ])res- 
snre on tho soil air ami al other times to decr(-ase that 
jiressni-e and, as a resnlt, there is a nearly constant ten- 
d(Micy for air to leave oi- eiitci- the soil on this acconnt, 
and it is jiosslhle that this factor in soil ventilation may 



209 

be stronger tlian any other, on account of the gi'cat fre- 
qiiencv with wliich tlie clianges recur. 

248. Movements of Water and Soil Ventilation. — The 

water whicli enters the soil as rain uiiist displace a volume 
of air ecjual to the rainfall which penetrates the soil and 
then, M'heu this water is again lost by the soil, whether 
by percolation or ])\ ca])ilhiry or root action, the same vol- 
ume of air must again l)e i-eturned. In a climate where 
the rainfall, whicli penetrates the soil, is 24 inches dur- 
ing the growing season, two cubic feet of air per square 
foot of surface enters the soil in consecpience. 



WAYS OF IXFLUKNCIXG SOIL VENTILATIOX. 

Thei'c are impoi-taiit means and methods of controlling 
and modifying the i-ate and extent of soil ventilation, 
which ai'e undei' the eonti'ol (d" the farmer. 

249. Soil Ventilation Modified by Tillage. — ^Xearly all of 

the operations of surface tillage modify the rate of entrance 
or escape of air from the soil. Plowing effects a sudden 
and complete change of aii- in the soil to the depth stirred 
and in the spring, wlien niti-ates are deficient, and the 
pores largely closed with watei-, this breaking up of the 
soil may be very Ixmelicial. 

The thorough ])reparatioii of tlie see(lhe(| hid'ore ])]aiit^ 
ing, so strenuously insisteil upon I)y the best jn-actieal men, 
has a portion of its rational j)asis in the need of soil ven- 
tilation ; and deep subsoil ing, when done at such a time 
as not to puddle the soil, must always pi-ofonmlly affect 
the re]ati(m of air to soil, as avcII as of moistnre. Indeed, 
all of the operations of soil loosening serve, not only to 
admit air more fi-eely to the soil stirred, but th(! undis- 
turbed ]x»rtions l)eneath will also be better ventilated be- 
cause of the surface loosenine;. 



210 

250. Rolling and Harrowing For Soil Ventilation. — It fre- 
quently happens, especially with small grains in the spring, 
when tlio season has been nnusnally wet and evaporation 
large, that a crust forms upon the surface, partly Ly shrink- 
age, partly by the crumb-structure breaking down and 
partly by the deposit of soluble salts between the soil grains, 
thus closing up the pores and greatly impeding the en- 
trance of air. Under such conditions the harrowing or 
rolling of small grains after they are up owes its advan- 
tages in part to the better soil breathing it secures, by 
breaking the crust. 

But it will sometimes happen, when small grains are 
rolled immediately after seeding, if the ground chances to 
be a little too moist, that soil ventilation will be so much 
hindered by the packing as to result in defective germina- 
tion and sickly plants. In one case a crop of barley was 
so much affected in this way that a serious reduction of 
yield Avas the result and the plants, even when mature, 
were so evidently influenced, that the rolled strip, between 
two adjacent areas not rolled, but in other respects the 
same, showed in strong contrast ou account of the smaller 
plants. 

251. Underdraining For Soil Ventilation. — When heavy 
soils are undcrdrained they are so iinicli more deeply and 
better aerated that this is one of the chief advantages of 
that method of land improvement. In such cases the roots 
of plants penetrate the subsoil so much farther, and earth- 
worms and ants burrow so much deeper, that with the 
decay of the roots the more or less vertical galleries formed 
by these agencies permit much freer and deeper soil ven- 
tilation. 

Then when the under clays dry o\it, as they do after 
draining, great numbers of shrinkage checks form and in- 
to these both the roots of plants and the free soil-air pene- 
trate and are brought togetlier. 

After this last stage of soil improvement has taken place 
the bringing in of carbonic acid with the air leads, through 



211 

its action ii2>on the lime, to the flocculation of the minuter 
soil particles and thus to a more extensive granulation of 
the whole subsoil, -which in turn extends the soil ventilation 
still more widel3^ 

But all of these effects upon the soil are only the meana 
which permit the underdrains to render their greatest serv- 
ice in permitting a strong and extensive movement of air 
into and from the soil ; for once the soil is oj)ened up in this 
way, the air, through the action of the wind, changes in 
barometric pressure and changes in soil temperature, read- 
ily enters the soil, not only through the surface above but 
throughout the whole length of the underdrains. 

^Vlien it is seen that changes in soil temperature and in 
atmospheric pressure make such marked changes in the 
flow of water from springs and from tile drains as are 
shown in (337) and (338) it becomes clear that the move- 
ments of soil-air into and out of tile drains must be even 
more marked than the movements of ground water. 

252. Influence of Vegetation on Soil Ventilation. — In the 

case of such crops as clover, which send long and somewhat 
fleshy roots down deeply into the subsoil, tliere are very 
many and important passageways opened up after the roots 
decay, Avhich greatly facilitate the deeper and more rapid 
change of soil-air, and, as has been pointed out, the re- 
moval of water by the living roots must also draw into the 
soil a volume of air equal to the amount of water used, 
except in so far as this is made good by the rise of capil- 
lary water fi-om below. 



212 



CHAPTER X. 

SOIL TEMPERATURE. 

253. Importance of Soil Temperature. — Xoiic of tlie chem- 
ical, physical or biological changes essential to the devel- 
oj)ment of plant food in the soil and to the action of roots, 
can take place in the absence of the energy stored up in 
the soil and indicated by its tenij^erature. When the tem- 
perature of the soil falls to 32° F. nearly all the life 
processes become dormant and for most of the cidtivated 
crops and higher plants these cannot begin until a tem- 
perature above 40° F. has been reached. All living bodies 
must have their temperature maintained between certain 
limits in order to have growth take place. 

254. Soil Temperature at Which Growth Begins. — Accord- 
ing to the observations of Ebermayer growth will not be- 
gin, with most cultivated crops, until the soil has attained 
a temperature of 45° to 48° F. and it does not take place 
most vigorously until after it has reached 68° to 70° F. 
Neither do the niter germs begin the formation of nitric 
acid from humus until a temperature above 41° F has been 
reached and its greatest activity is not attained until the 
soil temperature has risen to 98° F. 

255. Best Soil Temperature for Germination. — There is, 
for most seeds, a certain range of soil temperature under 
which germination is most rapid, under which the plants 
become most vigorous, and which ensures the highest per- 
centage of plants from the seed. This general truth should 
never be overlooked in the spring when it is possible to 
plant in a too cold soil. In the table which follows are 



213 



f>-ivoii the best soil tein])(M-iitnr(^s and the lowest and ]nif]\- 
est toinporatnrcs at Avliicli certain seeds have been observed 
to e'eruiinate. 



Name of Plant. 


Best Soil Temp. 


Lowest Soil 
Temp. 


Highest Soil. 
Temp. 


Sachs. 


Van 
Tiegham. 


Sachs. 


Van 
Tiegham. 


Sachs . 


Van 
Tiegham. 


Wheat 


84'= F. 

84 

8t 

93 

79 

93 


SIT. 
83 
80 
93 


4l»F. 

41 

44.5 

48 ■ 

49 

54 


4l»F. 

41 

44 

49 


104» F. 

104 

10-i 

115 

111 

115 


99° F. 
100 


Poas 






115 
















70 
89 
81 
99 


42 


82 


Turnips 




10:^ 








32 




99 





















The two important facts fixed by tliese ckta are: (1) 
The soil temperatures at which the seeds of most cultivated 
crops germinate best, lie between 70° and 100° F., with 
an average of about 85° F. (2) The soil temperatures 
below which germination does not take place are between 
41° and 54° F. From those it is clear that seeding should 
not begin until the thermometer will show the temperature 
of the soil at the depth of planting, well up toward 70° 
F. during the warmest portion of the day. These state- 
ments should not be understood as advising against the 
sowing of clover seed early in the spring, whih^ the frost 
is yet on the ground, under conditions where it might not 
be possible to get a stand otherwise. 

256. Observed Soil Temperatures. — The temperatures 
which the soil does attain at ditferent depths during the 
diiferent months of the growing season Avill be of inter- 
est in connection with the statements nuule in the last two 
sections. In the two tables which follow are given the 
mean seasonal variations of soil temperature at two sta- 
tions, one in this countrv and the other in Europe. 
1.3 



214 



Table shoivi.ng the mean monthli/ soil temperatures, at State 
College, Pa ., by Dr. Frear, and at Munich, Germany, by 
Eberniayer. 

At State Collegb, Pennsylvania . 



Depth. 



3 iiiclios.. 

G iiicliOR.. 
12 inclios.. 
24 iiiclies.. 

5 9 inclios 

11.8 inches 

'i'A.l inches 

35.4 inches 



April. 



"F. 
4:^.74 
4:^ 08 
42.69 
41,43 



May, 



op- 

55.13 
54,72 
53.83 
51.45 



June . 



"F. 

67.29 

66.34 

65.03 

61.90 



July. 



>.p 

70.16 
69.75 
68.89 
66.42 



Aug. 

-TpT— 

6.S.70 
68,49 
68.66 
67.41 



Sept. 



"F. 
61 32 
61.70 
62.73 
63.59 



At Munich, Germany. 



44.65 


56.79 


61.11 


67.26 


64 09 


44.31 


57.51 


60.06 


66.16 


63 61 


44.40 


53.58 


59.11 


63.12 


63.55 


43.56 


51.24 


.')7.33 


62.92 


62.26 



58.31 
57.88 
58.82 
58.51 



It luaj appear tliat tlic temporatures recorded in these 
tables are too low to be in liannony witli the comparatively 
high teniperatnres i2,iven n.s llu' best for i;'erinination. It 
mnst bo understood, bdwcvcr, thai the avcrago must bo 
lower than wonld be fi)iiiid in the soil dui-ing the warmest 
portion of the \h\\. In regard to the minininm tempera- 
ture at which germination takes ]daee it will be clear 
enough that the April i-ecords for soil t<'ni|H'rat ure are qnite 
in liarnion\- with thost' iiiN'on for iicrniinat ion. 



257. Influence of Soil Temperature on the Rate of Germi- 
nation. — Tlie more (luickly seeds are |)erniilled to gei'mi- 
iiate after tlu\v are phieed in the soil the liigher will be 
the \\vv cent, of seeds growing and, as a rnle, the more \ig- 
orons will the ])lants be. Indeed, seeds of low vitality 
placed in too eold a. soil often fail to germinate at all. 

ITaberlandt found that, when corn would germinate in 
3 days at a tein])erature of (>r).-> ' F., it re(|nired 11 days 
when the soil was as low as 51^ F., and {[(dli'iegel showed 
that when corn was ])lanted nnd(M- a mean tiMiiperatnre of 
48° only 2 ont (d" 10 kernels spi'outed in 42 days; that 
under the same temperatui'e rye germimite*! in 9 davs, 



M'intor uiieat in 12 days, and barley and oats in 13 days, 
Avliilc ciKMunhc'i's did iiot i;crniinat(' in i'2 days. 

258. Effect of Soil Temperature on Root Pressure. — The 

power wliieli sends the soil moisture into the roots of plants 
and np into the leaves is osmotic pressure, developed, by 
the warmth of the soil, and nnless the soil temperature 
is sufKciently liii;li phinis may wilt, as Sachs has shown, 
where lie demonstrated that ])nmpkin and tobacco plants 
wilted badly, even at ni<>-lit with an abundance of moisture, 
as soon as the soil Icuipcrat urc^ fell much Ixdow 55° F., the 
moisture not risiun- last enough to eomijejisate for even 
the slow e\ a I MUM I ion dui'iuii" the night. 

259. Influence of Soil Temperature on the Formation of 
Nitrates. — Tlie nitrates in tin; soil do not develop until the 
tem])erature luis risen above 41 ' F. ; tlie action of the 
germs is exti-cmely fcn-ble at 54" and they do not attain 
their maximum actixily until a soil temperature of 98° has 
been reached ; but if the cai'tli IxH'oines as warm as 113° F. 
then the action is nearly stopped, it being as weak as at 54°. 



CONDITIOXS INKiaiKNCING SOIL TKMl'KKATUUE. 

260. Specific Heat of Dry Soil. — When the sanu- lunnber 
of heat units are given to likc^ weights of different kinds 
of soil their tem])eratui-es are not raised throug4i the same 
number of degrees and this is because their s])ecific heats 
(40) arediffer-nt. 

From the determination of r)endei- it appears that the 
number of heat units i-ecpiii-ed to raise the temperature of 
100 lbs. of water and lOO lbs. of soil of different kinds 
from 32° to 33° F. is as stated in the table which follows: 



L' 1 (I 



I'ablc of Mfii <'i/ir Ih ttl of (Irii soifa. 



Wat.w 

Moor iMti't li 

lllllllllM 

HmmiI.v Iiiiimiih 

Liiiiin I'icli ill Iiiiimiih, 

< 'lil.vn.v lllllllllH 

I/IIMIII 

I'lini irliiy 

HiiikI 

I'lU'it cliiilk 



N... ..(• l.iMil iiiiilM vr. 


■|'(>iii|i(iriitiiro < 


•r KHi 


■ luil'IMl l<> I'lliMK 1(1(1 ll>H 


II.H. iiI'dM- (III' III 


i|ilicii- 


I'loiii 'M" \'\ lo ICC I''. 


lion <>r Kil) li«M( 


llllitH. 


Iliiiil iiiiils. 


u],'. 




1(M).(KI 


.s:i.(X) 




22,15 


:m.M 




2(1 W. 


m.iv 




II II 


Hit 07 




1(1. (IJ 


•M.{)Z 




Ifi.'AI 


■MM 




I4.t)(l 


HH.CIH 




III. 7:1 


!)l».2S 




lU.Utt 


41. 0i: 




18.48 


a7.4i 





1 1, is clciir iVmii lliis hiMc lli;il. iiiiicli more licnl is fc- 
(|iiii-('il III niisc llic l('iii|icr;il HIT nl wiilcr I liniiii!,li (Uic dr 
nrcc llciii 111' :i like wci^lil nf i\\-\ soil, ;iii(l liciicc lliiil, a 
tirv Sdil will warm in llic smisliiiic iiinrc capidlv lliaii a 
iimisl, soil can. 



261. Specific Heat of Wet Soil. Thr .lill'cicnccs in (lie 
\\'('ii!;lil per ciihic IikiI oI <lrv snils and llic d i Hcrciiccs in 
llicir walcr cdiilcnl. ;";rc;illv allcci llic spccilic |ic;il iir llic 
r;ilc al which llic surface |ciii|icral iircs will rise under llic 
same cdiid il ions. 

S.iiid has a small ea|i:icilv Inr walcr and mi lliis accniiiil 
is naliiralK warm, ImiI ils I'reali r wciidil |"'i' •■nine loot 
acis as ;iii niTsel, Icndiii;': le make il cnlder. II a hxisciv 
packed cla\ loam wcijdis V<> Ihs. per ciiliic indl and a 
s;ilid\ soil jUli Ills, and llie Iwo hold '.'>'■'> per ceiil. and IS 
per cell!, of waler respecl i\ d v, when capillarilv salur- 
aled, Iheii llic iiiiinltcr of decrees l'\ llial M»0 heal imils 
will raise llic leiiiperal lire of a ciiliic fool of each soil when 
salnraleil, Ii;ilf salnralcil and Av\ are i';i\'eii hehtw: 





Sal uiiidxi. 

:i 1" \'\ 
2. US 


Half Mill iiialKil. 

r. ' !■'. 


l»iy. 


Hiiixh Moil 




It. 1)2" F. 


( May liiiiiii 




02 


OMCO 




DilllM 


.42 


.ni 


8.9 



Olio llniiisiiiid lioiif. units would i-iiisc {\\o di ITcrciiccs in 
toiiipcriiturcs to \.'2 \ f). 1 .-iml -'!'.> , iiiid<iiiii- il clciii' lliiit 
the (I i llcrciiccs in wciii'lil .'iiid in wulcr ('(inlciil i:rc;ill_v iil- 
■lllicncc I lie decree (A' \\:\ mil li. 

262. Influence of Color on Soil Temperature. — Tlui color 

<»r :i soil, csiH'ciiiJIv wlicii drv, so llnil llic rule of cviipora- 
it((n i'l'oiii ils siirt.'icc is snnill, has a in:irl<('(| inllnriici' on 
tlu! Iciiipcrat 111-'', cNcii ill ('onsid('ral)l(' dcpllis. Wollny 
made* a scries of cNpcriniciils lo iiolc llic cllcrl ol color, 
using wliilc iinirMc diisl, and lanipMnck in diUcrciil pro- 
portioiiis, lo secure d i llVrcnl shades ri-(»iii lii;lil i^rev l<i Mack, 
in which he placed l\\() I jicianoiiiclci-s, one willi llic hull) 
just beneath I he siiid'atH! and I he ol her I iiurhcs below. The 
tciii|»eral iires were talscii e\'erv two lioiirs of IIh' ^i \ and 
the resulls areiii\'cii in llie hible bejow, loii'elher with those 
of a similar Iri.il usiii"' ncIIow ocIm'I'. 



T<(hl(' »lun(uii(f thr iiijliuiii-c of color <ni. the lent jxrafKre of noil. 





At the Surpack. 


At 


FoiiK Tn< 


11 KH DBIOP. 




l^lack. 


Dark 

urey. 

32 39 
82.90 


Mod'rn 
groy. 

31.98 
32.45 


Liglit 

wroy. 

30.94 
30.10 


Black 

-op— 
28.33 
15.20 


D.irk 
BH^y. 

28.46 
14 25 


M((d'ni 
Krey. 


Liglit 
prroy. 


Mean temp.. 
Variations.. . 


"F. 
32.82 
31.. 55 


op. 

27.83 
12.50 


"F. 

27.20 

11.85 




Dark 
brown. 

3l.7(S 
31.95 


Modinni 
brown. 


Li«lit 
brown. 

" "F. 
30.93 
29. 9U 


Faint 
brown. 

■ F.^ 

M.70 
27.05 


Dark 
brown. 

"F. 
27.29 
12.30 


Modinin 
brown. 

—op 

27.19 
12.15 


Lixlit 
brown, 

27.34 

u.80; 


Faint 
brown, 


Mean temp,. 
Variations... 


"F. 

:u.«5 

31.75 


"F. 
20.40 
10.75 



yroin this table it, a|)pe;ii-s that the diirkest soil, whetlier 
black or brown, was more than a de^-rco wanner lliaii the 
light soil at. four inches deep; and that the. black soil had 
a daily v;ii-ialioii in teiiiperiit iirc at loiir inclus iiior(! than 
3° F. greater iIkhi ihc li.oht. soil, ;iiid the diirk brown soil 
one of L.^T)" !•'. 



863. Iiilliiriicc (»r 'r(>|)(i|',rii|iliy oil S(ul 'l'ciii|i(iiiliirc. Thr 
(|p^'l'(>(< III ilirl ilijll lull III llir liiliil iiirrniT Mill! llir illri'fli III 
• if IIk* fi|n|ii', wlirl liri' riiriii;' fii:!, wimI, imrlli i>r mimiIIi, limy 
I'M'i'l. II llllll'lvcij illlllicili'r ii|iiin llir li'lii|M'i'ill III')' iA' llli^ soil 
iiihl ji.'irl iriiliii'l \ ii|iiiii il:. iliiirii:il i'iiii,".i'. Tlic l*'iii|ii'ni 
Illi'Kiil II ilil] I'i'il cliiy Mill, ii|iiiii a IrN'i'l liililr, ami ii|inii ii 
Hiilllli cSlHillirr :Jii|ii ll;-; alu.illl, is , win rmillil III llic Mill' 
llir(< llii'rr iii('l|i':i |(» lio IIM rcj il'CMrll I cil m llir laMc lu'ldW: 

tShiui'inil till inlliifiiii n/' fo/mifniii/i 1/ ii/iini miil ti iii/» riitiirr. 



ImnD III' Hull,, 


Dii'i II llinMiw riiM Htiliii'ACli). 


l><l loot. 1 '.'l»l l'.M>l 


:ii(l loot. 


lloil olliy, ftiilll II nl(>lit\, ,, II (III II II III 

Itixl i>ln,v, Ik vol miiTMOK,, ..i.n. ,< 1 


7(1, !l" 1''. 
1)7, 'J 


IW,I" K. 
lift, 4 


(Ill,*" K. 
ita,(i 

2,8 



||lM'(> ll l.'l MI'CII llial llir I'lll'l'l ol 11 JUilllll (AlKiSIII't' IS l<> 

iiiiikc II ili iTcrt'irM' ill lriii|u'i'al iiic nl' Irdiii a lillli' iimn^ tliaii 

;i ' I''., Ill llic iiirrafc In.il, III a lilllc lr:;:i III llic si'ciukI and 

IliinI I'lvl. 

'riic I'ciiuiii Ini' I licM • tlilliTt'iiccs will lie ri'iiilily iiihIci' 

Mjni.il III. Ill a . hills I'l' l''i<';. (II. Sii|i|ios(' A (1 ;"> I! to r(>|>- 

iT'.ciil a •('(•! idii of a |>ri;iiii 
(if ;am,;liiiii' I'alliii.", ii|t«iii 
III.' Iiill A K II. wli.M-o A l<: 
\ |M I lie MiMil ll sl(i|M> mimI K H 

is I lir iii'ii ll. < h\ accoiiiii 
(if llir 1111 linl licili;', tli 
irrl l\ \ III iral i'\rr llic hill 
llir ',.>iilli ■,li.|ii' rcrt-ivos HH 

KiikTi lull, n..,».Ki.ujl'.v"— I """■'' """'' '"•'' '" " ""''• 

'•'" """" ,.r liiiK- tliaii III." north 

slopo lis IIh' liiu> I «'• is loii-'vr than llio lin.' I .'•. 




2(M liitluciii<' o( l.odsfucss inul U ucvciimchh o( Surraco on 
Roil 'IVinixMiilurc. W luii a iirM r Nil \t r\ iiii<\oii. ami 



L'li> 



(-(|irciiill\' i I' cdNriTil w i 1 1 1 liii(i|i , IIm' l;ir;'i' iiiiiHiiiil III Miir- 
fjicc i'\|i.,:;((| 1(1 llii' : ly nml In llir :iii- |mtiiiiI:i IIic liriil, ul 
llif .iirriii-c, soil III lir Idsl, ni|ii(ll_v in wnniiiii^' llir iiir iilnivn 

ami llli' I'csilll i llii' (|rr|irl' sciil rrlllilillM ill. II ln\vrr Iclll- 
|MT,lllirf. Sn, In", il' llii' "nil in InnCC illjil n|)c|l, llic < I l\V 

siipci'lifiiil liiNir licrniiic;; w'linii aiid Ileal:, llic air, wliili^ 

|||(< I • ilh'lili;'; caiiacilN nf llic npili nil |.ITVclll;', llic 

||(.;i| iVnlll liriliv rnll\c\r(| (|cr|,l\ l.clnw ijic ; lll'larc all'l il 

luw'cr Iclll |icimI iii'c I (lie null 

266. Iiilliiciicf ol Siiirii(;(- Tilli(j;c (»ii Soil 'r«'m|Mi uliirc. 
Wlicii I'niii ,"rniiii(| w a . cull i\ aliil ;; iiicIk:; (|rc|i a; miii 
paicil willi |.;i, ill iillcniiilf ;^rnii|i,s. ul' I'mir mwiH, llic iiiciiii 

|('lll|ii'l'al HITS III' llic Huil ill llir lil'Ml, M nil! IIImI lllil'il Id'l. 

Iirlnw llic snil ;^lirrc(| WIIH I'nillMJ In lie .Sl{" |«\ Wll I'l I M T ill 
ihc lir, I Innl ami ..'.H" I''., aii'l .'Wi ' I''. t'<'H|)<'<'l i V<'l.y in llm 
'ccniidaml lliinl Iccl nii I Ik' /'iniiml rcccivJM'^' llic. HllllllnWi'l- 
cull I \ al inn. 

2(i(;. IiilliHMicc of Chemical and PhyHusal ChanncH on Soil 
T«Mii|)crHtiir<!. W'licii lica\\ drc;; iiii<':i nf fanii viinl nianiirc 
arc |)ln\\c(| ill, .111(1 when heavy i'i'n|);i are liinieil iimhr Inr 

;.'|-ee|| liiaillil'c, llli' rei'iiiclilal inn W'llicll is ttcl. Il|) ill lIlOlO 

iiialerial : re:. nil . in a iiica:.nre lA' heal, which waniiii liio 
soil ill llic same wa\' ihal a maiiiiic licaji heal;, when jcr- 
nicnlin^''. In<lcei| all nf llic : le|i: in llic rnriiialinii (>\' lli' 
trillcH ill llic ml I'cilll III llli' e\(illlll<ill nl .Siillic ||<al. 

A^llill, when I he ;.||l'l'ace:: nl' drv .'inil ;'raili:i liccniiie liinJH'* 
Iciicd willi waler, whelher hv rain or hv i-a|)illary innv<" 
iiieiil:'., :-,iirlaec hiranii in Inrciii." llii' waler In :iirrniiiid 
l.h^^ Hnij /^I'liiiis /MiicralcH u Hiiiall ainniinl nl heal, which 
llfTcchs, ill sn far, lln' nil leiii |)ei'at lire. 

267. IiilliMiicc ol ItaiiiH on Soil 'r<'iiijM-ral.iiH'. Heavy 
niiliH which lall u|inii lield and |iciielralc ihe ml niiiy <)X- 
ci'l, very iiifirkcd cIIccIm ii|inii ii leiii|)eral iirc on iiccoiinl of 
rlu'. rchilivcly hi;.di H|)ccili<' heal nl' ihc waler iih f()\i\\y,[\fi\ 
wilh Ihal nf Ihc soil. 

II llic al iiMi' |ihcrc \:-\ warmer lliaii llic (|cc|ier snil, art 



220 



niav 1)0 the case in the spring-, and if rains fall which re- 
sult in heavy percolation, a large amount of heat is con- 
veyed rapidly and deeply into the soil with the water and 
the temperature of the ground, two to four feet below the 
surface, may thus be very materially raised. 

268. Influence of Evaporation on Soil Temperature. — 
There is no factor, except the direct sunshine and the direct 
radiation of heat away from the earth into space, which 
exerts so strong an intluence on the temperature of the soil 
as the ©vaporaition of moisture from its surface ; and the 
chief reason why an undrained clay soil is colder than one 
well drained is the cooling eifect associated with the larger 
evaporation of soil moisture. 

To evaporate a pound of water from the surface of a 
square foot of soil, by means of the heat contained in the 
soil, makes it imperative that 9GG.G heat units be expended 
to do the work and this, if withdrawn from a cubic foot of 
saturated clav soil, would lower its temperature some 
10.3° F. 

The diiference in temperature shown by the wet and dry 
bulb thermometers measures, in one wav, tlie coolino' eifect 
of evaporation; the wet bulb often reading as much as 15 
or even 20 degrees lower than the dry one, under otherwise 
identical conditions. 

Table showing the in/tuoice of rapid evaporation upon the 
temperature of the soil. 



Date. 


Time. 


Condition of 
weather. 


Temp, 
of air. 


Temp, of 

drained 

soil. 


Temp, 
of un- 
drained 
soil. 


Differ- 
ence. 


April 24 -j 
April 25 ■{ 
April 26] 
April 27] 
April 2S| 


3.30 to 
4 p. m. 

3 to 3.30 
p. m. 

1.30 to 
2 p. m. 

l.?0to 
2 p. m. 

7 to 8.30 
a. m. 


Cloudy, with brisk 
east wind. 

Cloud.v, with brisk 
east wind. 

Cloudy, rain all the 
forenoon. 

Cloudy and sunshine, 
winci S. W. brisk. 

Cloudy and sunshine, 
wind N. W. brisk. 


(■60 3 
(■64 
[45.0 

[53 

[45.0 


"F. 
66.5 

70.0 

50.0 

55.0 

47.0 


"F. 
54 00 

58.00 

44.00 

50.75 

44 50 


"F. 
12.50 

12.00 

6.00 

4.25 

2.50 



221 

In the table above are given the observed differenoes 
;n temperature of a "well drained sandy k>ani and an ad- 
jacent black marsh S(3il, n()t well drained, the observa- 
tions being taken simnltaneonsly and the differences in 
temperature being due largely to differences in the rate of 
eva])oration in the two cases. 

MEAXS OF COXTROLLIXG SOIL TEMPEKATURE. 



269. Effect of Rolling on Soil Temperature. — In the spring 
of the year, when the soil is naturally cold, the first effect 
of rolling is to cause the soil to warm deeply at a more 
rapid rate, and Fig. 62 shows how strong this influence 
may be. In extreme cases the soil temperature, at 1.5 
inches below the surface, has been found as much as 10° F. 
higher than on entirely similar and adjacent gTound, not 
rolled, and 6.5° at 3 inches below the surface. This dif- 
ference is due to the better conducting i>ower of the soil, 
on accoimt of its firmer texture, and is in spite of the loss 
of heat due to greater evaporation which takes place from 
the rolled surface. 




Fli 



-Shdwini;- tin 



•t nf nilliui;- nil soil tciiiprriituri'. 



The average difference in temjierature of soil on eight 
Wisconsin farms, at the season ^\•hen oats were germinat- 
ing, was found to lie as given in the table below: 



222 



Time. 



2 to 4 p. m. . 



Mean air 
temp. 



65.37" F. 



Mean soil temperature at 
1.5 inches deep. 



Rolled. 
71.69» F. 



Unrolled. 
68.57° F. 



Mean soil temperature at 
3 inches deep. 



Rolled. 
67.330 F. 



Unrolled. 
64.39" F. 



Here is a mean dirt'ereiice of ."J. 1 F. at 1.5 inelies, and 
2.9° F. at -'5 inches d(H'p in favor of tlie rolled snrfaee. 

270. Influence of Thorough Preparation of the Seed-bed on 
Soil Temperature. — It follows, from what has been said, in 
previous ])araiiraphs, that the practice of thoroughly pre- 
paring the seed-bed before sowing or planting mnst have 
the effect of decreasing the capillary rise of cold water 
from below and its loss by evaporation from the soil. This 
then would tend to concentrate the sun's heat in the seed- 
bed itself, hrst by lessening its rate of conduction down- 
ward, and second by diminishing its loss, by lessening the 
evaporation. in the spring, then, early and thorough 
preparation of the seed-bed tends to make the seed-bed 
warmer ; it diminishes the loss of soil moisture ; it increases 
the formation of nitrates, thus making the soil richer; it 
hastens and makes stronger the germination and it enables 
one or more crops of w^eeds to be destroyed before the crop 
is u]) in the way of cultivation. ITenoe there is much to 
gain and little to lose in the thoi'ough preparation of the 
seed-bed before planting. 

271. Controlling Soil Temperature by TJnderdraining. — 

When land naturally too wet for tillage early in the spring 
has been thoroughly underdrained, the soil is brought into 
fit condition for seeding much earlier than would be pos- 
sible without this improvement, and one of the great points 
gained is the warming of the soil to a greater depth, on 
account of the removal of the watei- and the lessening of 
the loss of heat by evaporation. 



CHAPTER XI. 

OBJECTS, METHODS AND IMPLEMENTS OF TILLAGE. 

Tilling the soil is one of the oldest of ag-ricnltural arts, 
and (hiring its long practice very many methods have been 
adopted and tools devised for securing the ends sought. 

272. Objects of Tillage. — The term "tillage" has been 
applied to the different methods of working the soil in or- 
der to secure the conditions needful for the growth of cul- 
uvated crops. The chi(4' objects which tillage aims to 
secure are : 

1. To destroy and pre\-ent tlie growth of weeds and 
other vegetation not desired ii|)oii the gi'ound. 

2. To place beneath the surface manure, stubble and 
other organic matter whei-e it will not be in the way and 
where it may be converted rapidly into inimus. 

3. To develop various degrees of o})enness of texture 
and uniformity of soil conditions suitable to the planting 
of seeds and the setting of plants. 

4. In still other cases the object of tillage may be to so 
modify the movements of soil moisture and of soil air. 

5. In still other cases the objects of tillage may be to so 
change conditions as to make the soil either warmer or 
colder. 

TILLAGE TO DESTROY WEEDS. 

It mu&t ever be kept in mind that wherever weeds are al- 
lowed to grow they are removing from the soil both avail- 
able moisture and plant food in the form of soluble salts 
and, to Avhatever extent this is permitted, to that extent is 



224 

tlio possible yield of any crop lessened. No soil can mature 
a iiiaxiiinun ero]) of eorii when weeds are |)ei"niitted to grow 
with it. Neither is it possible for an orchard of any kind to 
eonie iirto beariiii>' as ([uiekly or to ])ro(lneei as viiioi-ons 
trees wheic the soil between and beneath them is occiipicMl 
by either weeds or grass. It may be thought that so long as 
'the weeds are destroyeid ujxm the ground thiey return to it 
whatevei' they lia\'e taken out ainl therefore cannot leave 
the soil pooi'er. 'i'o this it must l)e said 'that whatever 
moisture is i-emoNcd is a ])ositive loss because it is carried 
away by the winds; the nitric acid that is taken up and the 
potash, phos])horic acid and other ash ingredients are also 
larg'ely a positive loss so far as that season is concerned for 
they are removed frcmi the soil moisture and converted into 
dry matter in the tissues of the weeds wIumt the cro]) can- 
not use them. Kvvw if the weeds are killed while the crop 
is yet on the ground they cannot furnish Food for it for 
they are likely not to decay soon eiiougli to become at once 
available. 

273. The Best Time to Kill Weeds. — The l)est time to kill 
weeds is just as the se'eds are genninating or while they 
are yet very small. When this is done but little moistun^ 
is lost through them and they render but little jdant food 
insoluble. in the thorough and early ])re])aration of the 
seedbed many weeds are destroyed by killing them just as 
they are coming m]). So, too, in the case of a grain field, 
M'hich is rolled after being seeded and is then harrowed, the 
rolling hastens the germination of the weed seeds and the 
harrowing tluni throws i\ivni out into a dry soil which kills 
them. If such a field is again hai'rowed just aftei' the grain 
is up a eiecond cro]) of weeds may be destroyed and the 
yield made gi-(^ater as a consequence. 

In the case of potatoies and corn it is A-ery easy to destroy 
at least two cro])s of weeds before the corn or ])otatoes are 
large enough to cultivate, by harrowing before and just 
aft('r the plants are up. This is very important because it 
not only saves plant food for th(> croji but it can ])e done 



225 



so iiiiicli more clicaplv ami vapidlv with tlic l)roa(l ]]\i;lit 
harrows and wccmIci's than it can lalcf with the rultivator. 



274. Weed Seeds Do not All Germinate at Once. — It must 
he rcmemherod in ]ian(llini>' soils to kill weei^ls that the seeds 
do not all o-erininate at onee. The tiivt harrowinii' which is 
done to kill weeds niav itself hrinji' up from l)elow seeds 
which were too deep in the i;rounil to i;r()W or it luaj cover 
some seeds which were Iviiii: upon or too close to the sur- 
face to g'erminate, hence fre(|ucut cultivations for hoed 
crops are needful. 

275. The Best Tools for Weed Killing. — The tool which 
Avill do the most t'tfective sei'vicc in killin<i' weeds depends 
upon the character and condition of 'the soil and the size of 
the weeels. When they are not vtt fairly out of the ground 
or are just coming up and before a root system has been de 
velojx'd there is no tool e<pial to a medium weight or light 
s])ike-toothed harrow rejn'esented in Fig. r)2a. The stiffer 
and moi-e compact the soil is the heavier should be the har- 
i'<iw oi' rather the deeper it sliouM be run in the ground. 




l'"li;. ()2;i.--'rilliiij;- li.irrow, licst tool for killing .voiuik weeds. 

The tilting harrow, constructed so that the teeth may be 
iiudincd forward or backward, is one of the best forms as, 
with this arrangement, it may be made to^ run deep or shal- 
low as desired. 

On sandy soils and other soils when very loose the form 
of tool represented in Fig. (j-j may be used to kill very 



220 



yomi^ii,' weeds before iliev nre well routed; but this is not an 
effective tool when we'i'ds li;i\-e a start nor where the soil is 
at all liai'd or heavv. 




Fic. 63.— Wccdor. 

276. Cultivation After the Harrowing- Stage. — When 
])laiits ha\c hceoiiie too lar_i;'e lo ])eniiit tlu^ harrow or 
weedei" to he used to advaiitaii'e a tdol with broader teeth is 
needed. ( 'iilli\at ion or iiilertiiiaiic should begin as soon 
as the first iVesh weeds start and great pains should be 
taken to work so close to the row that all the soil is cither 
stii'red or eo\-ered Avith a thin layer of fresli soil. Few 
realize how close it is possible to work to a row Avithout 
either covering the plants or seriously injuring the roots, 
until tliey have learned |o do it. it is early and fi'e(|uent 
harrowing and careful close tirst cultivation that insures 
scrupulously clean lields and the largest yields the season's 
rainfall will peianit. 

277. Cultivators for Intertillage. — When harrowing has 
been ])r<i|)eily practiced intertillage may begin with a tool 
whose teeth ai-e about 2 inches wid(> and tliei'e should be 
enough of them to 'thoroughly stir the whole soil surface to 
a depth of two an(l one-half to three inches. Fig. G-t shows 
a good set of teeth for soils not too heavy, while Fig. 05 
shows a t(^ol which should not as a rule find a place in well 
cared for lields, for the teeth arc too wide and too few for 
good general work, 'i'hey an^ wasteful of moisture, waste- 
ful of fei'tility and liable to do too much root i)rnning. 



227 




Kh;. r>4,-A type <<( ynoil cult ivnlor. 

( 'nil ixaloi's willi riii,i(l tcclli like tliosc ol: Fiii,'. <»•> do l)et- 
teo" work as a rule 'than those of the spring tooth typo rt']> 
rescntod in Fig'. 04, for the reason tliat the tiTonnd is 
stirred more couiplctclv and to a more uniform depth. On 
natnrallv nudlow soils tlic s])i"ini>' tooth is ^'ood ;ind wliere 
the land is vcrv stonv it is safer a^'ainst breakini:'. 




liiiiiiiini II iiiiw 



Fjg. 65.-Ciilliv:il(ir wiili Im. \\u\<- Irclli for -cuitmI use. 



228 



278. Easy and Quick Movement of Teeth. — A xcrv ini- 
]»(irt;iiit fcntiirc of a ridiunor walk iiii;- sulk v cultivator is to 
liavc I he i;auus of Iciilli so swuuii' fi'oiu the carriaiic 1liat a 
slii>iit ctVovt will produce a cpiick aud cciiaiu uiovciucut. 
Tliis is iudisix'usaMc in ordci" lo work (dose to the rows. 




279. The Teeth of the Cultivator Adjustable. — Auotlicr 
ini|)(M'laut t'eatui-c sidkv cultivators should possess is the 
]»ossil)ilit V (d' tiltiuii the i;aui;s so as to allow tlicni to work 
luori^ deeply in the soil toward the ceuttr of tlu' row in llio 
\i\\v\' staii'es of cnltixalion hecause then the roo'ts near tlu^ 
rows have developed (dose to the surface, and deeper culti- 
vation in the centei', where the soil is iiior(> exposed to the 
sun, is ueeded for etfeet ivcness as a niuKdi. 



280. Covering Weeds in the Row. - It soiuetinies lia|)peus 
with ihe most careful nianau'enieul that weeds will oct suidi 
a start in the row tlia't elthei' hand lioeiuu' must he resorted 
to or (dse a tool must he used whicdi will throw euoui;h 



229 




Fig. 67.— Ciiltiviitoi- which fan Ite use<l to covei" weeds in row. 




14 



Fig. 68.— Tool far sliiillow surface cultivation. 



230 



earth to coA'er the weeds in the row. A good cultivator for 
this kind of work is represented in Fig. 67. The levelers 
represented in tlie rear of the discs are intended to throw 





arden cultivators. 



llie earth back to prevent ridging when the tool is used for 
ordinary cultivation and ridging is not desired. 



281. Garden Cultivators. — Two good forms of garden cul- 
tivators are represented in Fig. 69, where the upper one is 
to be used early, when the plants and weeds are small, and 
the lower one when the harrow-stage has passed. In the 
garden as in the field the best time to kill weeds is just as 



231 



"the seeds are p;eriaiiiatiiiii and emerging,' from tlie soil and 
the harroAV-'tootlied eidtivator is vciy effcetive in doing this. 
It stirs the snrface thoronghly enongh to throw the young 
weeds ont and cause the soil elose to the snrface to dry 
sufhcientlv t(. kill tlieia. Much worry and hard work will 
be saved hv the timelv nse of this or a similar tool. 



TILLAGE TO MODIFY SOIL TEXTURE, 

282. Soil Texture and Tilth. — Texture of soil, like the 
texture of cloth has reference to the size of the elements 
which give it its evident structure ; and just as the threads 
of a piece of cotton, a piece of woolen or a piece of silk are 





Fig. 70.— Sliowiiig the grauular character nf a soil in good tilth after 

cultivatiou. 



made by twisting together varying ninnbers of small fibers, 
making the threads coarse or fine, so is it with soils ; they 
are comprised of granules of varying sizes formed out of 
ultimate soil grains which are cemented togethei* more or 



less liniilv. l-'i-;. 70 rc|>i'rsciits llic l(\liir;il ("Icincnls of u 
r\n\ Idtiiii ill |ircllv i^nod lillli. 'I'licrc nrc shown seven 
si/.es of <;riiniiles liiri^c eii()ii>;|i lo Ke reiidily disl ini^iiislied 
willi llie n;ike(l eve, :iiiil e;ieli si/.e is (•(•ni|»(ise(l of line soil 
^■filiiis <■( iiieiiled l(i^cl lier. All ;ire re| ireseiilcd ii:illll':il 
si/.e iiiid were e;i rein 1 1 v dni wii Iroiii :iii :i<'l inil siiinple I iikeii 
Iroiil il lliree ilieli iiiilleli iis.lel'l iil'ler llie <Mi lli Viilor. 

Tlie ^'ninnies were sorled l)\' ineniis of :i series (d sieves 
:ind llie reliilive :iiii(MIIiI id e;i<'li si/.e of i;r;inilles is re|»re- 
seiiled liv llie sliiidiiii; ill llic \i;ils wliere it is seen tliiil llie 
I.Mr^csl size eoiisliliiles llie snnillesl pjirl of lliis soil, :ind 
No. r> llie liiri;('sl: porlioii. Tlie liiiesi n'rnde. No. S, is :ilso 
lar^'(dv e(>iii|»oscd (d' e(>iii|M)iiiid i;r;iins, iininv l;iri:,c enough 
lo |te el(';il'lv d isl iii^ii islied liv llie niuiided e\(', lull liinilV 
IlKM-e td llie llllilinile i;i';iilis wliieli \\<Te niMied idl from 
llie Iiii'i^'er i^riiins liv eiill i\ :il iiii; ;iiid diiriiii;' llie process of 
screen ini;'. 

.1 lisl. ;is Woolen clollis dilTer when llie thri'iids :ire 
(»l I he siinie si/.e hec;iiise some ;ire Iwisled I roiii liner :iiid 
olliers Iroiii courser wool, so soils diller in Iniviiii;' llieir 
i;r:innl(s nnide o| conr-.er or liner sn\\ piirlndes ceinenled 
to^cl her. 

'riieii, loo, jiisl ;is one (dolli iiniv diller Irom iinolher in 
liiiviiii;' ils ihreiids looS(dv Iwisleil, while nnother is Inird 
I wisled, so one soil in;i\' di iVer from :iiiol her in I he deiirec ol 
lirinness willi \\hi<'h the soil [cirticles ;ire cemeiileil lo- 
iL!,cllier. 

Still !ii;;iiii, jiisl :is one fiihric imiv he loosclv wo\eii 
while jinolluM' is line, so <tne soil imiv Inixc ils i;rinmles more 
slroni;iv c(inenled lon'clher lliiin :nio||ier, mcikiiiii' it luird lo 
wtu"k :ind lie;i\ v while the other is liulil ;iiid mellow. 

A siind dillers Irom ;i soil in heiiii;' coni|Mised ol siin|)l("i 
Mcparnle _i;r)iins, nsmillv (d' rather hir^c si/.e, while a chiv is 
composed \'erv l:iri;('lv of extremtlv line i^rannles made 
from llie linesl of |>arl icies. 

A soil is in ii'ood tilth when its i^rannles are neither loo 
line nor loo coarse, and when thev are not loo tii'inly 
<'(;'iii(Uil('<l togelher. 



283. Why Good Tilth and Good Tillai^c Arc Important. 

Il is clcnr I ruin ihc roiiiidcd I'onii ul' llic ^riiniilcs (il Hoil 
hIiowii ill l'\^. To, I hill when llicv iii'c ■ iiiiissc(| l.o^cl licr vvil.li- 
oiit l)('iii<;- cnislKMl il x'ci'v liir^c iiiiKiiiiil: of iiiH)ccn|)ic(| s|iiix'<i 
must cxisl ; lliis iiiiocciipicd s|»;ic<' in ;i soil is iicolcd I'nv IIk- 
liio\'»'iiiciil 1)1 iiir ,'iiid (d Wiilci'; for llic s|ir(';idini; (Mil, of 
the r<iol lilicrs ;iiid I'dol li;iirs, :iiid hir llic iMniif ol' iiiicro- 
or^iiiiisiiis wliicli dc\('lo|i llic ;i\;i i LiMc ii il i-o^vn used liy iili 
1 lie liiii'lici- |»l;iiils. 

II I lie iiriiiiii l( s lire 1(1(1 liir^jc ;iiid Ion |(i(iS(d\' |tii<'k('(| |,Im! 
soil Ids llic r;iiiis full lliroiioh ji |(,(i freely iiiid does iiol, 
liriii^' it liiicis r;i|(idlv ciioii^li li\' eii|»illii ril y lo iikm;!, tlie 
iicc(|s ol croits. II I lie ^r;i miles ;i re loo si mil I mid loo close 
llicii llic \\;il( r iiio\('S loo slowly, loo iiiiicli is rcliiiiicd \)y 
e;i|ii ll;i I'll V ;iiid I here is loo I il I le ;i i r. If I lie i.- rmiii les iire 
homid to<;cllicr loo slroii/^lv, llic soil is loo liiird iiiid IIk; 
i-oots iii'c miiiMe to set il. iiside in iiiiikin^' llieir ii(lv!i,ii(!<! iiikI 
this luck (d ri'cciloiii rc(|iiccs the \icld. 

284. How Texture and Tilth Are Developed. The soil 
|i;irli<dcs iirc dniwii toLi'cllier into the rounded i^riiiiii les hy 
the lension (d the soil wiitcr in the smiic vv;iy lliiil, Wiii(^r 
lornis ils(dl iiil<t spin vex when sprinkled on ii diisl covered 
lloor. As lon^- iis (hereiirc hir^c open H|)iiccs in the soil not/ 
lillcd with Wilier the wilier is nil llic time driivvin*;' ilsfdf to- 
gether, Iciiiliiiii to loriii spheres, mid in lliis Hyslcni of piilirt 
the soil piirti(des l»ecoiii(! involved mid iire driivvn l,o^<^thcr 
jilso. .\s the Witter is lost, hy eviiporiit ion iiiid the; hiiI|,h dirt- 
s(d\'cd l»cc()iiic loo slivtii^' lo rcimiin in solnlion they iinr dc- 
posilcd upon mwl hetween the <;riiiiis iiiid ^rmiiiles teiidiii*!,' 
to (•(■iiicnl t liciii loud her. 

285. Difference Between Soil and Potter's Clay. VVlieii 
t he i^r;! miles (d'ii (i ih soi I ii re ill I hrokcii down iitid H(fpiirii.l,(!(l 
into tlicii" lilt i III iite ^riiiiis we liiive tlu- puddled (vuidilioii so 
liitiil to ci'<t|)S, hilt the (die the potter strives to scitiirc; lo 
niiikc his Wiires (dose in tcxliirc :iiid si roii<^;. In the piid- 
dle(| soil mid poller's (dii v ciioii^h of I he Ljrmiii Ics liiiv<' hecii 



234 



broken <lo\vii to fill the spaces between tbe larger simple 
grains and finer granules not yet broken down to make a 
close textured, impervious material in which no plant can 
thrive, and through which neither water nor air can move. 

286. Early Spring Tillage. — The early stirring of the soil 
in the spring- prc])arat()ry to scciling lias for its niain ()l>j('ct 
tho changing of the soil 'texture so' that it will become 1st, 
warmer, ^d, dryer, 3d, better aerated, 4tli, better suited to 
lessen the raite of evaporation of the deeper soil water, and 
5th, to hasten the development of weed seeds so they may 
be destroyed before the cro]) is in the way of killing tlicni. 




287. The Disc Harrow. — (hw of the best tillage tools yet 

devised is the disc harrow represented in Fig. 71. There 

is no harrow which so thoroughly pulverizes a soil in the 

spring after fall ])lowing as this tool. When set to vork 

deep the draft is heavy but the amoinit of work it is doing 



235 



is relatively large. To ])ut a [)iece of fall i)lowing in the 
best shape the harrow should be lapped half and in doing 
this the furrow between the two sets of discs will he en- 
tirely filled and the surface left level. 




O m. 

f'n,W:Vljni*l ^ irl^l 



I'm. 72.- Siiriii^;-tootli harrow. 

Where small gi-ains are to follow corn or potatoes the use 
of this tool will often make the plow unnecessary. 

On the upland prairie soils and others natural I v uiellow, 
ground for corn may bo plowed in the fall and fitted in the 
spring with 'the disc harrow with good results. 

288. The Spring Tooth Harrow. — On new land in wooded 
comutries and where the tields ai'e roniiii and stoiiv the liar- 




Fio. 73.— Spiko-tootli or sniootliiiig liiirrow. 



236 



row r(^])r('s(nt('(l in Fi<)-. 7i' docs _i>()0(l work. Tts weight 
iorcH's it into tlu' soil iiiid tlu^ cliisticit.y of the tcctii prcA'ciit 
tlicin tVoiii l)('iiii>- hrokcii, hut such tools can ncxcr do tlie 
(lc_<;i'('c (il |>nl\-ciM/.ini; that the disc hai'i'ow a('co!n])lishcs. 

289. Smoothing Harrows. — When the soil has been pnl- 
A'(M-ized with ihc disc or other tool and it is (h'sii-ed to h'ave 
th(^ surface iiioi-c neai'lv cncii, or where the* soil is naturally 
\cry mellow, uiakiuii,' less force necessary to chaniic the 
surface texture, then the heavier 'wei,i;hts of tiltiui;' har- 
rows, Fig. 7o, nniy he used to _ii,'reat advantaji'e on aeeoinit 
(d the iireatcr area whi{di may he co\'ered with them in a 
dav and their lii-htci- draft. 




Fi(!. 74.- Tlu' plank. ■!•. 

290. The Flanker. — It is sometinu's desirahle to h^ave the 
Burface ])articulai'ly smooth without finninj;' it and at the 
same time to crnsh lumps. Tliis may l)e done hy means of 
a plaid<er nnidc of thi-ee to five 8- or 10-inch plank 
bolted to-ivthci' with their e(l,<>-es ovei'lapi)inii' as repr(>sented 
in V\ix. 74. The tool is b(\st made of oak j)]ank two inches 
thick and (Miilit to twelve feet, lon,«i'. Such a. tool cannot 
lake the place of a I'oller wlier(> it is desired to firm the 
iinnind. 



291. The Use of the Roller.- -'riie roller is used chiefly 

when it is desired to linn the surfaceaml to hel}) cover seed, 
especially when sown hroadcasl. In other cases it imav bo 
used to crush clods or to com])ress the furrow vsliot^s after 
the sod plow. Agai)i when a orei(>n ciop like; rye or clover 
has been turned under for manure, or where coni-se litter 
luis heen plowed undei', a roller is neiMled to c()imi)ress the 
soil and eslablidi good cai)illai-y connection with the deeper 
soil water. It is sometinu's used to d(W(dop a mulch where 
grain is rolled after it is up. 



23^ 



III Jill of llicsc (;;is('s wciiiiit is one of the cssciitiiil iciit- 
iii'cs of the fool. A I'dllcr t'of tillaiic sliouM li:i\'c a, vvciiilit 
of about 100 ll)s. to the I'liiiiiiui;' foot and a (liaiiictcr ot 
alxtuf 2 fecit. 




Kid. 75. Twi) t.vpcs of i-dUcrs. 

Two tA'ix's of rollers are represented in V'\'^. T"), tlic one 
made of bars hein^' desii>ne(l to ernsli clods more cimpletelv 
and 'to leave the snrfa('<' i-id^ed so as to' be lees likely to be 
inllnenced bv the wind driflinii' the surface soil. 

292. The Harrow Should Follow the Roller. — Tii most 
cases wlien it has been desii'able to use the rollei' to smooth 
or firm the surface a liii,ht hai'row shoidd follow it quickly 
in order to prcNciit uiinecessarv loss of soil moisture, Ix;- 
cause the iirmiiiii' draws the deeper watei- to the surface, 
tlie surface temperature becomes higher in the sunshine 
and the wind veloeity u'ear tlie smooth surface is greater; 
ea(di of wliicdi favors the rapid loss of water. 



293. Danger in the Use of the Roller. — On heavy soils, 
when they ai'c a little wet, injuiMous i-esuits may i'ollow the 
use of the roller j\ist after ])lanting or seeding on account 
{A' the close packing, excluding tlu^ air from the seed, wliieli 



238 



iiilcrlcrcs willi (|iiick ucrniiiiiiliinii. Tliis diiiimT is i;rc;il('sl: 
wlifrci fii-jiiii liiis Ix'cii sown willi ;i drill. 

'rii(> use of iJic i-()||('i- wlicii llic soil is ;i lit i Ic loo 'acI mnv 
;ilso inloi-rcrc willi ilic fonii.'ilidii of iiilric ncid in ihc soil 
l»v iimkiiii;' il loo (dose :iiid \an wet. In smdi ;i cjisc llic ini- 
"i('<li;ilc nsc ol ,1 li^lil |i;irrow vonld onlv i-chiin llic nioisl- 
iii'o .ind ni:d<c llic r;ilc of nil rilicni inn slower. 

294. The Plow. 'I'lio |>lo\v ns :i lillii,«iv tool is used for 
(wo disliiicl |)iii-|ios(s, Isl, l(. ;ilt('i' llic Icxhirc, loniiini;' 




I'Mc. Tti. Sliowllii;- llic |ii'iiicl|i!i' ol III,' |Mil\ rri/lim arlinil oT llic plow. 



iToiu il conipnriilixcly liard soil ;i dcrp nnd incllow hivcr of 
ciirlJi ; I'd, lo Imrv Kcncnlli llic surlncc weeds mmI oilier 
vof>'ot.iil ion ol" niniuire wliere il iiiiiv deciiv riipidlv and bo 
coiivc'rled inio axailaMci plaiil food. 

If you will o|icn a hook, i)lii(*in_i;' the iiiiii;ers upon iho lly 
}oi\[' in froid and the tlninihs uiuKt th(> lly leaf in I ho back 
and ahnipllv IxmhI iij) llu^ cornei" it. will bo soon that every 
loaf is slipixMl over its n(>i,i>,libor. What takes place is rep- 
resented in l*'i_i!,'. TC*. Had ])ins been ])iit throiis2,li the book 
before attempt inf>' to bond the loaves the bendins>- M'ould 



2.'}!) 

Ii;i\<' tended lo ciil llie |iiiis into ;is iii;ili\ [Heees ;is llici'(! 
were Iciivcs, jiisl iis seen in h'ii;-. 7<!. 

Now I lie |»lo\v li;is exiietlv I his kind (d" elVeel, upon llic! 
Iiirrow slice; il lends lo ninke il di\ide inlu thin hiyers 
wliicli slitle (i\('i- one ;inolliei' jnsi, iis llie leiiNCS (d* I lie book 
did, and il is heeaiise of lliis sort, (d" iU'lioii tlial, a |)lo\v |)iil- 
vci'i/.es a s<»il as no oilier lool can. 

295. How Plowing" May Puddle Soils. W'lien a soil is loo 
wet. its i;i-annles are so easily lirokeii I hat the plow is liable 
to slioar all tlio coarser ones into two, three, or iiiorc! Hlic(!H 
just as llie pin has been sliee(| in |''ii;-. 7<>, thus dest roviii<;' 
its tilth b\' pnddliiii;- it. 

296. How Plowing May Correct Texture and Improve 
Tilth. — I I' a soil has i^ot ten onl of tilth, has beeoine cloddy 
or lias been partly puddled there is a shape of mold board, 
51 sla^'c of soil nioisliire, and a depth of fiin'ow slice wliicli 
will iielp to restore the lillli best ami ipiickesl. When siK'li 
a soil is the least amoiiiil, loo dry lo puddle the ])low will 
shear it into the thiiiiiesl- slices ; if si ill drier the layers will 
be thicker and will form coa rser n'l'a miles. 

When II inch too di'y no shear iii^' c;i!i I ake place at all, and 
the furrow slice is siniplv broken into coarse lumps. 

1 r \'on bend but a few leaves of the book at- a lime tli(M-e 
is but, little slippini;, but the thicker the |)ile of leaves ili(! 
i^'reater is the slidini;' and the greater is the lendeiuiy to 
sheai'. So it, is in jdowiii^', the deep furrow pulvei'i/es Ik;!.- 
ter and puddles worse than the tliin slice or shallow furrow. 

A^'aiii if yon bend the leaves i^'eii I ly there is lilil(! shear- 
iliji', bill if abruptly llie siidini;' is f^reat. So il you plow 
with the lo'\- mold Imard if I'iij,'. 77 yoii disturb llie tilth 
least, puddled the soil least, and leave the Ic.xliirc! coarsest; 
but if the sleep mold board (d" h'iii'. 7S is used there is tlio 
^'i-ealcst, danii'er of piiddlini;' if the soil is too wet and the 
<;i'ealesl opportiinit-y to piil\eri/.e the soil and iiii|)ro\'e tJi«i 
tilt li if the moist ui'e is I'i^iil. 

297. Forms of Plows. IMows are made with two fiinda- 



240 



iiK'iitallx- (lilh'rciit shapi's (lejj('ii(liii<i ii|iiiii llic cliaracfcr of 
the work which thoy are expected to (h). 

'Tf the chief object of the plov is to cut a. clean ftirroAV 
sUce and turn it over so as t(- coinph'tcily cover whatever 
may be upon the surface a shape i-epi-eseiited in Fig. 77 is 
used. 




I''J<:. 77. — Type of s-.d ],i(is\. wliirl; iiulvcrizcs' but little. 

If on the other hand the })riinary object of the phnv is to 
thoroaiglily ]iulvierize the soil, makiiiii- it (k'ep and mellow, 
a form represented in Fig. 78 mnst be nsed. Then accord- 
ing as one or thc' other of these t\V(^ chief objects vary in 
importance shapes of ])lo\vs will be chosen \vhi(di are in- 
termediate b(t\v<>en tlu^se two extremes. 



298. Kind and Condition of Soil and Shape of Plow. — It 
must be ch-ar from the mechanical action of the })low that 
its form shonld be adapted to the soil. If the soil has a 
teoidency to be too open and porotis, and is nam rally coarse 
grained, like the sandy soils, it shonld be plowed with a 
steep mold board, a little over wet and as deep as other con- 
ditions Avill j)ei'mit, so as to break down the grannlation 
and secure the ch)S(T textnre. 

If the soil is generally too close in texture, is heavy and 
soggy, it needs the less steep mold board nsed when the soil 
is a little dry so as to shear into thicker layers and form 
grannies of larger size. 

If ph»wing mnst be done wheu the soil is a little too wet 



241 

use tlio less stcej) mold bourd and [)l()\v as shallow as other 
conditions will allow. 

If a soilhas heconu^ a little too di-yiand is noit pulverizing" 
fine enough, use the steeper mold board and ])low deej) for 
this will S])lit it into thinncu- hiyers, make tlu^ soil finer, 
and the tilth better. 

299. The Kind of Soil, the Shape of the Mold Board, and 
the Draft of the Plow. — Since the steepest mold hoard hends 
the furrow slice most and pulverizes most, it is clear that 
the work done is gi-eatest, and hence that the draft will be 
most. 

Since deep plowing |)ulverizes more than shallow ])low- 
ing the work done is more than in i)roportion to the depth. 

Since clay soils have more and larger grannies which 
must be sheared in two in ])lowing than sandy soils do, the 
labor of plowing must be greater. 

Since the granules of the soil are not as strong when the 
soil is moist as when dry it plows much easier, when in 
good condition. But if the soil has become too dry and yet 
must be plowed, it should be ])l()wed decjx'r rather than 
shallower. This is necessary to pulverize better, to get 
more moist soil on the surface f<»r the immediate seed bed, 
and to (piicker moisten and bring into condition the layer 
which has become too di-y. 

300. The Sod Plow. — IMie sod or breaking plow is con- 
structed so {.s to reduce the draft as much as possible by 
doing only the work needed to cut and turn over tlie fur- 
row slice. This is ac('onii)lislied by making the mold board 
very long and slanting so that the fui-row slic(* is 1 enit and 
twisted as little as ])ossible, as shown in Fig. 77; the chief 
work being to cut it and roll it bottom u]). 

The extremely obliipu^ edge of the share in the breaking 
])low reduces the draft in cutting (,if the i-oots by allowing 
the cutting to be done gradually and with a di'awing cut, 
just as it is easiei- to cut off a limb by letting tlx' l)la<l(' of 
the knife slant backward, drawing it across. 



242 



The extreiiuOv oblique coiistniction of this plow too, 
makes it easier to hold it steady when passing and cutting 
off sifrone" roots or other obstruction. 




Fkj. 7S'.— 1\v)iu 111' |ml\ cri/iii;; pluw with sti't'ii niDhiboard. 

301. The Pulverizing or Stubble Plow. — It will be seen 
from Fig. 78 that this plow has a much steeper mold board 
and much less oblique plowshare, the object being to bend 
the furrow slice as abruptly as possible before it is tnrned 
over, for this is what pulverizes the soil, giving it the loose, 
fine, open texture sought. 

302. Mellow Soil Plows. — Soils which are sandy and 
naturnlly very iirellow may be ))l(HV{''d with a ])low having 
the mold board less steep and more like that of Fig. 79 in 
shape. With such a form as this the team may cut a wider 
furrow, and thus cover the ground mort^ raj)idly, because 
the draft is less. 

When soils are very heavy and stiii" it may al^o be de- 
sirjihle to use this type of i)low, simply because the draft 
would be too heavy for the team with tht^ tyjie which pul- 
verized the soil more. 

Again very loose soils which have an extremely tine tex- 
ture and tend to clog will often clear better from the 
less steep mold board because the pressure comes more 
obliquely against the surface. 



243 



303. Draft of Stubble Plows.— The amount of labor in- 
volved in pl()vviii«2,- a licld is so lari>'e nnder tlic best possible 
conditions, and it is so easy to make it unnecessarily large, 
that it is important to understand the principles upon 
which the draft depends. 

]\rr. Pusey in Eniiland, in 1S4(), made a series of trials 
on the draft of plows in soils of different kinds, using 10 
different pl(;\vs. We have coanbined his results and give 
them in the table below: 

Tabic shoiving the draft of plows in tests made in England 
and in America. 



Kind of Soil. 



Loamy sand 

Sandy loam 

Moor soil 

Strong loam 

Blue clay 

Sandy loam f J. C. Morton). 
Stiff clay loam (N. i'. 1850) . 



No of 
plows. 



Size of 


Total 


furrow. 


draft. 




Lbs. 


5 in. z 9 in. 


227 


5 in. X 9 in. 


250 


5 in. X 9 in. 


2*50 


5 in. X 9 in. 


440 


5 in. X 9 in. 


661 


6 in. X 9 in. 


566 


7 in. X 10 in. 


407 



Draft per sq. 
in. of furrow. 

LbT 

5.04 

5. ,55 

6.22 

9.72 
14.69 
10.48 

5.81 



Prof. J. W. Sanborn made an extended series of trials in 
1890 in Missouri and later in Utah and the average of all 
his trials gives a draft of 5.!>8 lbs. per sq. inch of the cross 
section of the fun-ow slice. Separating these trials historic- 
ally, omitting those in the blue clay in England, the re- 
sults stand: 



English trials 1840, mean draft 7.41 lbs per sq. inch. 
American trials 1850, " " 5.81 " " " " 

1890, " " 5.98 " " " 



304. Draft of Sod Plow With and Without Coulter.— A 
set of trials with a sod plow near the type of Fig. 48, in 
clover sod 2 years old,when the moisture present was about 
as high as it is prudent to work the soil, gave results as fol- 
lows: 



244 



Sod plow with wliool coulter. 
Sod plow witliout coulter 



Size of furrow. Total draft. 



5.575 in.x 15.08 iu. 
fiM'if) in. X 14.5 iu. 



DilTerenco. 



Lbs. 
296.25 
343.75 

47.50 



Draft per 

sq. in. 



Lbs. 
3.524 
4.453 

.929 



iJcsidcs (loiiiii" the work Ix'llcr tlic (•(Miller (liiiiiiiisli('(l tlio 
(lr;rl"t. l!(i..'!('> per cent. 

305. Draft of Sod Compared With Stubble Plow. — Auotluu- 
set. of triiils were made al I lie tiiiic of 304 (o ('oiiij);\i"C the 
stuhhlc tv|>(' of plow, Fig. 7S, willi thai of l^'i_i>'. 77, iuul tlio 
results uiv given below: 





Size of furrow. 


Total draft. 


Draft per 
sq. inch. 


Stubblo plow witliout coultor 

Sod plow without coultor 


5.87-i X 14.31 iu. 
5.325 X 14.5 iu 

DitTerouco 


Lb.s. 
4,52.4 
343.75 


Lb.s. 

5.384 
4.453 




108.65 


.931 



In this case itlie sliajx^ of tlie ])low altered the dralt 20.1) 
per ('('111., and 'lie di nerciicc is prol»al>l\ a iiicasiii'c ol the 
dill'ereiicc in IIh' ainoiiinl of piiKcri/.ing done liv llic two 
])lows. 

306. Influence of Difference of Soil Moisture on the Draft 
of Plows. A iliird .scries of ohserxal ions wias made on a 
elover sod with the same sod plow proN'ided wi'th a wlieel 
coulter, hut at a time when the S(»il was drver than when 
the other measurements were made. The results loiind 
\V(^re : 





Size of furrow. 


Total draft. 


Draft per 
sq. in. 


Clover .sod without coultor 


6.47 X 11.61 in. 
6.413 X 12.47 iu. 

DitFeronco 


Lbs. 
714.35 

664.82 


Lb.«. 
10.80 
8 616 








49.53 


2.181 



24{ 



111 lliis set (if I. rials l\n-, ('(iiillcr lijis reduced, tlu; dral't 
25.34 percent. 



Soil rather dry 

Soil in best condition. .. 



DiiTorDiice 



Sod flow with coulter. 
Draft i)or n(i. in. 



8.616 
3.524 



5.092 



Sod plow witliout coultnr. 
Draft per s(|. in. 



10.80 
4.453 



6.347 



l"'r()iii llii.-. cniiiiiiiilsdii ii is clear 'lliat tlic draft (d" llio 
])I()VV' is \-ci'v iiiiicli iiKidilicil |>\- ihc cdiidilidii ol' llic soil. 
'J'lie results sIkiw I lie dialt luore tliau douMeel wlieu the 
soil was drver. 




7(t. 'I'.vpc. (,r jiMili|l,i.;in 



^^^^. 



■^iiili''! I" riicllciu .sdils rc(|iiii-inn- lilllc jiul- 
vcri/.in;;. 



307. The Draft of Sulky Plows— It is gonorally claimed 

that tli(H draft ef sulkv plows is less 'rliau tlial of tlie frec- 
swimiiiiuo' iv|.es hecause tlie frictiou of the sole and land- 
.shle i.s transferred to the well oiled hearings cd' the cari-iage. 
The f(w records aceessihlc do not show a matfudal gain, 
when-th(^ influence cf the weight of the carriage and driver 
arc not(ledu(ted, hut where the draft is no greater on tlio 
team with the luau ridiug than wheu walkiug, and the plow 
15 '^1 



L>l(i 



call !)(• 1i:iimII('(I witli ('(iiuil I'acililv, there is :iii e\i(leiil nd- 
\iiiil;i;;e ill ridiiii; pluws siicli as I'^ii;'. SO. 




V'li;. Mi. Sulky 111- liiliii;; pluw. 



308. The Line of Draft. It is \crv iiii|i(>rt:iiil in the 
liaiidliiii;' <'!' a plow I hat the line of dnifl he just riii,lit- and 
such that a line ediiiieel iiii; the center (d d ra 1 1 A, Fiji'. 81, 
in I he iindd heard with I he ph-icc (d' at tatdinieiit le I ht phiw 
hridh' shall also lie in the iilane (d' the traces, as shewn in 




Km. SI. Dli-cclicni dC llir line of iIimCI U<\- \i\u\\: 



247 

tlu! cut l)y ihc line A, I!, I). II fni- ;iiiy rciisdii tlic line of 
(h'jif't l)i"('()iiics ;i lii'dkcii dill' lis A, ( *, I ) (ir I , •'!, .") (,)• 1, 1,5 
instead of 1, 2, .") I lie dnifl of I lie plow is iiiii<lc licMvicr. 

'I'lio lii'ciiilcst cni'c should lie exercised to li;i\-e the length 
(d the trjiees, or the hitch ;it the plow hridle niicIi tliiit IIk; 
jtlow "s,\iiiis free," re(piiroii: little or no pressure ;il IIk; 
handles to iiiiide it. I I a slead\' pressure in any <lirection 
is i'eipiire(| ;it the handles soinelhinii' is wronii and the team 
is dolnii more Anyk than is necess;ir_\' as \c\\ as the imin 
holdinii' t he plow. 

309. The Scouring' of Plows. There arc certain soils, 
whose texture is sn(di that the most perfect plow ^nrlac(3 
tails to shed them coniplet(d\' an<l in sncli cases the shapes 
approachinii' the sod-plow are more snccesslnl. iJiit it is 
a matter ot greatest moment that the niohl hoard possess 
not only an extremcdy hard linish, s(» as not to Ik; s(ti-at(died 
by stone or ^'rit in the soil, hut it must also possess an ex- 
tremely close texture so ;is to he susce|)t ihle of a very hij;li 
polish. If the !n(tal itself is ( oai'se oriiined there will he 
ine(|ualities e\'en in the hriiiht surface in which the line soil 
pai'ti(d('S may Iodide and thus (doj^- the jdow. 

310. Care of the Plow. - 'I'oo onat pains cannot he taken 
to nralntaiii a hrifiht clean surface on all |)olished |)arts of 
tli(^ plow and the necessary care to do this will always |)ay; 
this caution is douhly important where the soils ai-e in- 
(dined to (do<i. 

WliencNcr a plow is laid l»y, e\'en for a few weeks, its 
bright surfaces should he tliorouiihl\' (deaned, wiped (|iy 
and (Minted with a layer of 't he t hick mineral luhricant used 
for joui-nal hearin<i's, to |»re\-ent I'ustinj;: A little rusting 
nuiy ])i'acticall\' ruin a plow for use in a soil v\liich tends 1<» 
cjoji,' and a sin^^le winter of rusting' may injui'e a plow nioro 
than a full season of liea\y service in the field. 

311. Keeping the Plow in Form. A plow caina.t render 
liea\'y and joni;' continued ser\ice without <4'ettinjL!,' out of 
])ropei' form. The point, hecomes dull, too short and as- 



248 



sunups ihc i'onw sliowii in Fig. 82, iiish'iid of tlint in Fii»'. 
83. ]u this worn condition the inclination of the nioUl 




Kui. .S2.- Slicwiiii;- poiiil ol' plow wiirii iiilo li;i<l I 



Ixiai'd lo llic Inrrow slice is cliaiiu'cd, tlie plow lends lo I'nn 
on ils |»oisil. is more dillicnll lo hold, llic drafl hecouies 
liea\ier and poorer work is ddue willi it. 




ill 



I 



l''i(;. S.l. Slicw iii.u' poliil III' [iliiw ill ^■llo^l I'linn. 

Tlie lic(d of I he share (' in l*'ii!,s. Si and S,-> is especially 
liahle to i^ct into had t'oriii and dull, eausina,' the plow to 




iff"'''''!iiiiiiiiiiiiiiiiiiiiiiiiiiii^ 

J''ni. Si. Sliiiwinu liiM'l 1.1' pli'w ill I'liriii fur ilr.\ soil. 

Avina,' o\'(M' to t]i(^ land ami draw hardei', not oidv IxH'anse it 
is dnil hti't hecanse a stc^ady ])r(\ssnre ni\ist lic< exerted at tho 
liandles to pre\'ent the |)low from tippinu' to land. 




Fig. S5. — .S1iiu\ iiii; liccl ol' plow in I'liriii I'nr iui>ist soil. 

Tt. is sometimes necessary to tdian^e the form of tiie ])l()w 
to snit, a harder (H* more mellow coiidil Ion (d' I he soil. W hen 



249 



tlu;' soil is dry iiiid liiird tlui liccl iiocmIs to be set down, as 
sliown iit i\ Fi^'. 84, and tUv \Hni\t niiiy need to dip oven 
luon^ than in Ki^'. 8.'{, but when tlic soil is wot and niollow 
tlic shape shown in i'ii>-. SH is recpiired to prevent it draw- 
iiiH' l(i(f (Iccplv into the iii'onnd. 

In takinjj,' lh(* share to the shop for sharpen iiiu!; or sH,ling 
tho landsidc; shonhl accompany it in oi'dcr 'that the; bhudc- 
sniil h may lia\c a i;iii(h' in i;i\in^ it t he proper sh a |)('. 

312. The Jointer Attachment. One of the most useful 
atiiudimenls for a ph»\v is known as a, jointer, repi'esieu'ted 
in -Fi^'. S(i. This tool is used toi;reat ad\antai;'(' when con- 
siderabh': material neeils lo he tnriie(| imih-r, such as h)ng 
stuhbh", course manure or In turiiini;' uu(h'r a i!,i'een crop 
for manure. When tiiis is iise(| with the (h'ai;' chain in the 
furrow very loni;' weeds can he completely laid under tin; 
surface, leax'in"' the lironnd in oNcellcnt sliaix'. 




Kl<!. 8(i.— I'luw Willi jdlnhT. 



AVheu soil ground is to he plowed deep and left in slia|)e 
tor immediate piihcri/.iiii;' 'to lit. it, for crops this tool will 
olten render excellent serxice by cutting- out. a section of 
tho Hod, tnriiiiii; it into llie hoiltom id' the furrow, where it, 
AV'ill !)(■ completely coxcrcd, at the same lime lcavin<;' tin; 
upper ed<;'e of the fui'r'ow slic(; c(niipose(l oidy of c(jmpai-;i- 
"I'ivelx' loose ( ai-th. 



2 no 



313. Subsoil Plow. ( )iic of ihc mosl widclv used J'uniis 
of sult-s«»il |>lo\v is r('|ir('sciilc(| in l''ii;. S7. Il is iiilciidcd 
lo 1m' used ill llic li(Ht(iiii nf ;iii (ii'di ii;ii'v fiiiTdW, (Hic |il(i\v 
t'd'llnwiiii; llicdilicr ill dniiij^ llic work. 

M\l rciiicJ y i;(Hid jiidiiiiiciil is i'c(|iiin'(| in llic use (d llic 
siilisoil |d(iw l(t ;i\<>id piidd 1 i ii!4', winch is sun • to rcsiill h'oiii 
iisini;' llir lo(d when llic siilisoil is loo wcl. In liiiiiiid 
(diiiiiilcs tlic d;iiii;crs ;irc i;rc:ilcsl in llic spriiii;' iiiid Icasl. 
ill llic r:ill, :iii(| il Miiisl lie kc|)l in mind llnil llic siirhicc 
soil iiniv lie in i;(>od coiidilion |o plow wIkii llic snlisoil is 
iiincli loo wcl . 




(•'li:. > ., S oil plnXN. 

Ill scini.'iiid (diiinilcs llic dimmers of injuring:, llic soil 
•h'xlnrc :irc iiMudi less :iiid il is under siudi coiidilioiis llial 
subsoilini; is likely lo inoxc mosl |iiolil;iMe, leiidiiii; ;is il 
<loieis lo incrcjisc llic ;i\;iil;ilde iiioislurc lor ero|» [irodiicl ion. 



oit.i lars, M i;iii(>i)s AM> ri Mi'.s u|.' n.ow i \'(.'. 



314. Depth of Plowing. 'rii<> hesi deplli to plow :it a 
_i;'i\('ii I line, on :i i;i\'cii soil, lor ;i iiiNCii crop iiinsi Itc Av- 
<'ided on llic spol mI'Ici' cxcrcisinii' i^ood jiideiiH'nl willi il 



251 

l<iiii\\l<'(li:c III llic ii<<ils mill ci.iKlitioii- . Tlicrc •-.•iii l«' no 

"iMllc of 'I lllllllli" iol plowillii. 

As ;i i|;'iici ;il nilr in liiiiiii<l el i iiiii h- llic |i1m\\ never 
slioiiM .!;■<> (Icc|i('r lli.'iii III turn <i\cr llic ;-iirl:ii'c or i|;irk 
(•(.|(ii'c(| hivcr (if \vc;illiciv(| sdil. If (Iccpcr |)l(.\viii;j, is ddiir, 
tui'iiiii^' ii|» lln' iiiiwfiil lii'iTil siiltsoil, llic pidiliici is'ciicss 
{)[' t lie licld will lie rcdiiced. 

It, is \('r\' (leslr;il)lc Id (|e\('l(i|i iiinl iii;i i ill ;iiii ;i <lc<'|» soil; 
this is chnrlv prdACil l)V llic lie;i\ier cictps wliicli jiIwjivs 
j^iNHV iipnii *'l);ick furrows" iind llic sciiiiiv <iiies w lii(di ^tow 
ill "dc;id furrows" ;is coiiipii red willi llic n-l (d llic licl<l. 
W'licii ;i soil is lliiii iiiid llie siilisoil is (do-;c :iii<l lic;i\v it is 
olllv Sill'e lo deepen il ^r;idli;illv liV pictwillj; il lil'lle deeper 
cjKdi vciir or two, Inriiiiij^' under iis l;ir iis |)ossil)lc coiirsc 
iiiiimirc, sliiMde ;iiid ^recii crops to iii;ike the soil open iiiid 
form liiiiiiiis ill il. 

I'.'ill plowing iiKiv iisiiidlv lie ;is deep jis tlie soil will per- 
mil, ilo'Aii lo (■), 7 <ir even '"^ ilielics, Imt llie discs ;ire rel;i- 
ti\'el\' lew w lii'rc il is importiint to plow deeper llinn (I or 7 
incdics. W'licrc plowing is for siinill ^r;iiiis to he soweil ;it 
olic^i^ llie dcplli lii;iv ilsii;ill\' lie sliiil low, ."> iindies iH' lesM, JIS 
these lliri\c hesi in ;i sinillow sccillx'd. 

315. Best Condition of Soil for Plowing'. Ihere is m ei»ii- 
ditio'ii of moisture |)ecnli:ir lo cindi ;iiid e\'er_v soil id whicdi 
it, will he hd't with 'the hcsl le\l lire ;i 1 1 cr plowing', recpiirin^' 
thl(^ Iciist iiinoiinl. of tinishin^ work l<i pul il in liinil (•(iiidi- 
fion. if the soil isi|oo wet the (•riiiidi siriicliire -o cHSCIl- 
tiiil to il (diiy soil will he piirllv desi roved mid the soil 
])inhll('d; if too dry the fnrrovv slice will not -licjir in thin 
Ijiycrs iind 'the soil will not he pulverized line. The wiiter 
content, should he sindi lliiil llic iliiiii|» soil S(piee/ed ill the 
hand will Indd its form hut will ciisils' crnmhlc lo pieces 
an<l not, he iil nil pit-^l v. 

S(kI ^roniMl ciin iilwiiys he plowed il little wetter- tliiin 
coni, |)olii'to or stnhhle ;;rolllnl hcciilisc the r<iots lessen the. 
danger <d" pmhllin^- iind the shciirinji- (dfect of the plow is 
lc'«H. 



252 

316. Treatment of Ground After Plowing. — Groimd 

plowed liitt' in the fall, to ae-t as a luulcli, to allow the 
moisture "to penetrate deeply and to have its texture altered 
by thawing and freezing, should be left with the natural 
furrow surface rough and uneiven. 

If plowed in the spring when the ground is a little over 
wet and 'the turned furrow shows large;, polished surfaces 
the ground should be gone over with a. harrow but not ini- 
mediatdy, for if the soil is a, litth^ too wet i't sluudd be al- 
lowed to dry just enough so as to cnimble perfectly. 

If the soil is alrea<ly a li'ttle too dry and a crop is to be 
put on at once then the harrow should follow the plow 
closely, otherwise the soil will bcconu' hini|)y and the 
whol(>< fui'row slice may iHH'ome too dry for the hcsi gcu'mi- 
nation. 

If the j)lowing is for coi'ii, potatoes or the garden and is 
done some time before the ground is to be ])lant(Hl 'then the 
surface is better k>ft as it would be for fall plowing, pro- 
vided tlie soil is in good condition when plow^ed, because 
it will foi'm a better mid'ch, it will take th(» rains better, 
be less likely to become too mucdi eompaeted by the rains 
and will harmw down better when ])lanting time comes, 

317. Plowing for Corn in the Fall. — On soils whicli are 
naturally nu'llow, where large areas are to be plan'ted and 
the spring's work is crowded it is often best to plow for 
corn lat(^ in the fall, just before freezing. If such ground 
is to 1k^ manured ii can be plowed in then to advantage or 
if the manure is not too coarse it may be applied as a sur- 
face dressing during the winter and disked in the spring. 
If thie soils are very heavy and hixxo a tend(>iicy tO' run "to- 
gether -wath the spring rains then there is danger that the 
disc may not. be able to bring the field inti condition. 

318. Plowing Sod. — There are two methods of plowing 
sod, 1st, skini-])lo\ving, usually in the fall, turning over a 
thin sod to kill the turf, oxjiocting to cross, plow in the 
spring deep enough to bury the sod and turn up enough 



soil to work up lino and form tlic si'cd bod. 2(1. Plowing 
deep enoiigk at first to provide a sufficient soil to work up 
with a disc harrow and give the desired depth of seedbed. 
The latter inctliod usually rexpiires less time but the draft 
is heavier. It is usually bent in such cases to go over the 
surface with a heavy roller to press the sod home and lessen 
the danger of the disc turning them over. 

319. Plowing Under Manure. — If manure is coarse or the 

soil light it i, usually bctlcr lo place it under a deej) fuiTOW 
because it neieds more moisture to rot it and in heavy soils 
it will lot the air peiu'trate more deeply into the soil. In 
such cases it is better to do the ])lowing in tluv fall or as 
early in the spring as itlic: soil will permit. If the ground 
is a little too dry when ])lowed and seeding time is at hand 
the field should be tJKirdughly harrowed and lirmcd, using 
the heavy roller if necetssary in order to establish good 
(•a[)illary connection, with the deeper soil. Jf this is not 
done the soil above is liabh; to become too dry. 

When the manure is wcdl rotted it may be left nearer the 
surface to advantage, except in tho sandy soils where the 
air penetrates so deeply as to cause too rapid docom])osition 
of the manure. 

320. Plowing Under Green Manure. — Where a crop is 
'turned under for green nuuuire it is usually best tO' plow 
deep, 'to use the jointer and the drag-chain if necessary to 
get everything well and deeply buriecl. ]f a considerable 
body of material is turned under thorough firming of the 
soil af'ter ])lowiug will be beneficial. 

In green manuring good judgment is always required 
not to let the cro]> turned under exhaust the soil moisture 
too completely, for when this has occuiTcd a new crop 
starts under very unfavorable conditions, both because of 
lack of water and immediately available plant food, for the 
soluble salts are used uj) with the water by the green ma- 
nure crop. 



254 

320. Early Fall Plowing. — in vooious niid at times wlicro 
there is a (Icticieiicy of I'ain, wliei'c the soil is lioiit and 
when tlu^ amount of soil Jeaclifiui;' is small it is often de- 
sirable to ]>lo\v as early in the fall as the et'o)) has been vv- 
moved Iroiii iheuroiind, in order !(► save soil moisijni'e and 
to enahie the intrates and other soluMe salts to develoj) in 
sntlieient (piantity for the next season. Where crops hold 
the soil moisture low it may eNcii hecMtme neeessary ill 
dry elinnites to I'aise one only evei-y other year because 
the |)lant lood and the crop cannol l)e ]»roduce(I l)\' the; 
availahle moisture of a sini>,le season. But early fallowing 
in th'(^ fall will often render the full vear unnecessary. 



GROUND WATER, WELLS AND FARM 
DRAlNA(iE. 



CllAPTKIi XII. 
MOVEMENTS OF GROUND WATER. 

Of the watcf wliicli I'lills npiMi I lie l:iii<l (Hic poi'tinii iiiuls 
its way at oiu-c, hy surtacc How, into (lraiiiai;(' cliaiiiK'ls; a 
second puitidii is cvaporatcMl wlicrc il fell, Avliilc a third 
entors die iii'oii 11(1. 'I'liat portion which enters the ,i;roiin(l 
and is not returned hy ea])iihirily or ro(»t aetion constitutes 
the body of <>T<>und water which is the sourc-e of sup[)ly for 
wells and .spriniis and which recpiires removal hy land 
(Iraiiiau'e when too close to the suiiace. 

322. Amount of Water Stored in the Ground. — Tn most 
localities after |)assinii- a certain distance helow the earth's 
surface a horizon is rea(died where the ])ore space in the 
soil, sand and i-ock is tilled with water or nearly so. AVlien 
these pore sj)aces are lar<;(', so that water can flow through 
tiuMu readilv, wells sunk heneath the surface till with water 
to the level oi' the lii'ound water sui'face. 

In sands and sandstones lyinij,' l)(dt)W drainage outlets 
the amount of water may be as hi,<;h as 15 to JJS per cent, 
of the total volume of tlr(> rock so that where a coumtiy is 
underlaid with broad and thick sheets of sandstone, such 
as the Potsdam and St. i*etei-s in Wisconsin and further 
south, or the Dakota formation in the west, there is the 
equivalent of from in to :>S fVct <d water on the level for 
everv 100 feet in tlii(d<ness <d" the ro(d< formation, and 



256 



abundant supplies of water can always be found in such 
places. 

Tbe loose sands and gravels have a pore space of 20 to 




Fig. 



-Contour niai) of a hi'ld. one portion of wliicli has been tile 
drained. 



38 per cent, of their volume so that where these lie below 
the ground water surface and their volume is large an 
abundance of water exists. 



257 



In the soils and clays tlie pore space is even larger than 
it is in the sands and this too may be filled with water but 
here the texture is iisnally so close that a well sunk in such 




Fig S9. — Coutoiu- map of the sroiind water surface under the tield of 

Fife'. 88. 



material fills with water so slowly that they cannot serve 
as sources of water supply. 

Even in the hard crvstalline rock, like marble and 



258 



granite, there mray be as iniicli as .4 of a pound of watcn* 
in eacli cubic foot, but here again the 'texture is too close to 
permit such water to become avaihible in wells. 



323. The Ground Water Surface. — As the rains which fall 
in a given locality percolate beneath the surface they till 
the pore spaces between the soil grains and raise the level 
of the ground water. If none of this water drained away 
and none of it were lost by 'eva})oration the whole soil 
would have its pore spaces filled Avifli water and the surface 
of the ground water would coincide with the surface of the 
land. As it is, as soon as the surface of the ground water 
©eases to be level drainage begins and the water under the 
higher land is lowered until a condition is reached when 
the rate of drainage laterally exactly equals the rate of ac- 
cumulation of water from the rains. 

In Figs. 88 and 80 are shown tlie contours of the surface 
of a section of land and of the ground water beneath, both 
sets of contours being referred to the same datum plane, 
Lake Mendota, into which the water is draining. Here, it 
will be seen, the ground water stands highest where the 
surface is highest and lowest where the land is lowest. The 
arrows show the lines of flow and make it clear why the tile 
drained area needed that treatment. 




324. Seepage. — Almost everywhere under the land areas 
there is a slow movement of the ground water from higher 
to lower levels destined ultimately to reach some drainage 
outlet. This movement is known as seepage and Fig. 90 is 



251) 



a ercKss-set'tioii sliowiuii' liow tlu' walci' tldws frdui ilic ad- 
jacent liiglu'v lands and enters the ehanncls of streams, the 
beds of lakes and even the oeean itself. 




-Siiowinj;- 



iiitouis of niMiuul water surface in the \i(iiiiti 
Liis Aii.i;elcs Kiver, Cal. 



325. Growth of Streams.— The water wliieli maintains 
the low stage tloAv of streams finds its way into channels 

all along the banks and bot- 
toms rather than at isolated 
])laces in the form of springs, 
entering in the manner 
stated in (324). In Fig. 91 
is re2)resented the gronnd 
water snrface in the valley of 
the Los Angeles river, Cali- 
fornia, where it is seen to 
rise back from the stream 
and nj) the valley. This 
river mnst be draining the 
adjacent higher land and it 
Avas fonnd by actual measurement that the growth of this 
stream in 11 miles was 60 cubic feet of water per second; 
tlie water all entering by slow general seepage, there being 































[>= 










-^ 








^ 


^^ 


^ 


' 










i 












,=.^ 


,, 






l- 


















I** 






1^ 






s 



Fig. 92. - Profile .showing increase 
of the Los Angeles river by 
seepage in 25,978 feet. 



260 



no visible s])rini>'s or streams anywhere along the line. 
Fig. *.)2 shows the increase in 2r),!)78 feet, determined by 
ganging. 

326. Changes in the Level of the Ground Water. — The 

level of the ground water in a given scH'tion is nsnally sub- 
ject to changes, the surface rising and falling with the sea- 
son and with the rainfall of the place. The change may bo 
as much as 5 or 6 feet in a single season, as represented in 
Fig. 93, and wdien a series of dry or of wet years follow in 




Fl«i. 1(3. — Showing cIimjiucs in the level 'if llic >,'r<imi(] water surfjire during 

the season. 

succession the changes may be larger than this. It is clear 
from these facts that in digging wells whose water comes 
from near the surface of the ground water the bottom 
should be carried deep enough into the water bearing beds 
to leave it below the lowest stages of the ground water. 

327. Elevation of the Ground Water through Precipitation 
and Percolation. — In Fig. <JI is represented the unoccupied 
space in eight feet of five grades of sand, above standing 
water, after 2,5 years had been allowed for percolation 
under conditions where no evajKu-'ation could take place 
from the surfacie. The unshaded portions of this figure 
{represent the relative amounts of space into which rains 
may percolate for each grade of sand, as compared with 
the whole areft of the diagram; that is to say, if an inch of 
rain w^re to fall upon the whole surface of the diagram 
and it were occupied with the 'No. 100 sand the space 
into which tlve rain could descend is measured by the un- 
shaded area under 100; so for each of the other sands. 



261 



It will be .seen fnnu tlie diaii,i'aui that up to 12 inclics 
above the ground waiteT surface the space into which water 
can settle in either t^and is \«ery small and hence that a 
small amount of percolation will produce a relatively large 
elevation (if the iiround water surface at first. 



100 80 60 40 


20 


r 














_ _ — ■ — _- -_ 








1 




















— 


1 




■ J 


































^^i:=:^:>==J^-5=;^=^^^^::=^S^^NS^^g^:ss:g:g^^s=pr^3;,_ 




: >S=^ 





Fi(!. SA.— SliowiiiL'- ti>p jinifniut of unocfiipied snacc in complett'ly drained 
sands. Space between long rules, one foot. 

In a tank filled with rather coarse sand and provided with 
glass gauge tubes, as represented in Fig. 112, p. 293, to 
show the level of the ground water surface, a single pound 
of water added to the 14 square feet of surface raised the 
level of the ground water .31 inch. In another trial 
16.435 lbs. of water or .226 inch raised the surface 6.7 
inches. In still another trial the withdraw^al of 33.575 lbs. 
of water from the tank, or .461 inch, lowered the ground 
water 9.05 inches. 

In the table below are given the amounts of water re- 

Tahle showing amount of rain necessary to raise level of 
ground water after thorough drainage. 



Grade of sand. 


1 foot. 


2 feet. 


3 feet. 


4 feet. 


No. 20 

No.40 


Inches, 

0.874 
.433 
.579 
.370 
.242 


Inches. 

4.379 
3.551 
2.701 
1.592 
1.030 


Inches, 

8.. 5.50 
7.795 
6.454 
4.0-0 
2.635 


Inches, 

12,81 
12.19 
10.80 
7.. 573 
5.131 


No. 60 


No. 80 


No. 100 





16 



262 

quired to raise the surface of 'the ground water 1, 2, 3 and 
4 feet in the sands of Fig-. 1)4, after thorough drainage has 
taken place. 

328. Law of Flow of Water Through Sands and Soils. — It 

has been generally claimed that the velocity of liow of 
water through sands and soils is directly proportional to 
the effective pressure and inversely proportional to the 
length of the column through ^diich the flow is taking 
place. This means that to double the pressure will double 
the rate of flow but to double the length through which 
the water must flow will decrease the rate one half. A 
law analogous is fonnulated for the flow of fluids through 
capillary tubes and under certain conditi(ms of pressure 
and dimensions the law has been nearly fultilled, both with 
sands and capillary tubes. 

In practical measurements^ of flow it is found that the 
flow through some sands and some capillary tubes increases 
faster than the pressure while in others it does not increase 
so rapidly. 

■The law of flow here referred to has been designated 
"Darcy's Law" and has been expressed by the formula 

P 



V = k^ 



where 



V is the velocity, 

P is the difference in pressure at the ends of the column, 
h is the length of the column. 

k is a constant depending upon the size of the soil grains, the 
amount of pore space and the viscosity of the fluid. 

329. To Compute Flow of Water Through a Column of 
Sand, Soil or Rock. — Under the conditions where Darcy's 
law may be fulfilled the amount, of discharge may be com- 
puted by means of the formula derived by Slichter- and 
given below: 

1 Nineteenth Annual Report, U. S. Geol. Survey, Part II., p. 202. 
-Nineteenth Annual Report, U. S. Geo!. Survey, Part II., pp. 301-322. 



263 



q = 10.22 -^-rr— c. c. per second (1) 

^ //hk 

■\vliere 

p is the pressure in c. m. of water at 4'^ C. 

d is the diameter of the soil grains in millimeters. 

s is the area of the cross-section in sq. c. m. 

// is the coefficient of viscosity. 

h is the length of the column. 

k is a constant whose log. is taken from the table, p. 123. 

and 10.22 is a constant whose log. is [].009i.] 

If the pressure is measured in feet of water at 4° C, the 
length in feet, the area of cross section in square feet, the 
time in minutes and the diameter of the soil graii^s in mil- 
limeters the formula is 

q = .2012 ■ ■ cubic feet per minute. (2) 

//h k 

If the floAv of water oceurs under a temperature of 10° 
C. or 50° F. the formula may be written 

q = 15.30 - 1— r— cubic feet per minute. (3) 

Problem. — A cylinder 4 feet long, having a cross sec- 
tion of 2 sq. ft., is filled with saud whose grains have an 
effective diameter of .15 nnn. What will be the flow of 
water through it under an eifective pressure of 12 feet, 
when the temperature is 50° F. and the pore space is 35 
per cent. ? 

Substituting these values in equation (3) we get, taking 
the value of k from the table, page 123. 

12x(15)-'x2 . 

10.3 — - — r,T-7.f, — = .06532 cu. ft. per minute. 
4 X 31. bJ 

Problem. — AVhat would be the flow in cubic feet })er 
minute under the same conditions except at a temperature 
of 68° instead of 50° F, ? In this case use formula (2) 
and the results are, taking the coefficient of viscosity at 
68° F. at .0101 from the table below: 



204 



\-2 \ ( If))' \ ii 
-••'^..l..lx.|v:U..;2 •O'Hil.u.n.pM-.ni.u.l. 



'I'Aiti.K III. ('()<■ l]ici( Ills of i'isc(,si/i/ J'lir iiudcr far ixtn'oiin tciii- 
peratureti cen./i</i(i<fr. 



(J 


IMII|>(M'II- 


// coolllcidiil 


() li'iniMifn- 


II <'<)olli(Ml^lll 




llll'O 


ol' 


liiro 


..r 


coil 


tiKi'uilu. 


viHOoHit.,v. 


<'t>iit Iki'ikIk. 


viHCOMity. 







0,{)17H 


Id 


().()i:il 




I 


(1 (Il7'.i 


II 


()I2M 




2 


1) linitl 


VJ, 


11 i»i:!.| 




:i 


11 (III!) 


III 


(1 OIJO 




1 


(loiriii 

UAHWJ, 


i: 

IT) 


(' (1117 

II mil 




II 


o.oin 


lit 


II Hill 




7 


1) (iii:{ 


17 


(I IIIIKI 




H 


(ii:i.s 


IM 


II (iKn; 




11 


(i(>i:ir. 


111 


OIlKt 




10 


1) iii:ii 


•^0 


OOIUI 



330. Observed and Computed Flows Compared. Wlion 

sjiikIs 1iii\i' 1)c('ii soi'Icil into n'rjidrs of iiciirly miil'oi'iii Hi/o 
:iihI llir rllVcl i\i' d iiiiiirlcr ili'lrniiiiii'il hv I, lie luclhod of 
(^143) :iii(l llii'ii I III" lldw of Willi'!' llii'oiii;ii lliciu iiiciisiinMl 
ill such :iii ;i|i|i:ir:i( IIS ;is is ri'pri sciifcil in l^'ii;'. \K> llm oh- 
sci'Vcil Mini coiiiiinlril llows JUT I'clnfrd ;is nixrn in llic next 
luhlc. 



o^ 



>_ 



43 



^« 



. 










y 


■ 








/ 


.■^' 


- 10000 oc 


^ 


^ 


^ 


^ 




M)00 cc 


// 










■y" 


y^ 










^'l.Ji^ ?f.,... 


03 

....1 


0« 

...1.... 


Oft 


OS 


or 
1 



i"l(). !ir>. Shiiwliin ii|ii';iriil US I'or niciisiirliit; (lie How (if wiilrf llir(Ui;;li 
siiiids mill llic rcliUliiMs nl' How (o I In- (lliiiiu'lcis of llw siiiiil ;;i-aliis. 
IjIiics show I lu'urt'lit'iil How; dols, oliscrvi'il llow. 



L^c.r. 



>.\ 







' HiidSin,, /' •,!..:' Si J 



7 







5" 












Kid. OC- SlmwliiK llii' s.-niil uniiiis n.fi.i ri'd lo in hiMc uf (21"J|. .\iiliir;il 

Hi-/,.'. 



26G 



Table shoKnng observed and computed flow of ivater through 
simple sands of different diameters under a pressure of 
1 a. ni. of water. 



(irrado of 


Diainotor of 


Ob.sorvod 


Computed 


sand. 


Ki-ains. 


flow. 


flow. 




m. m. 


gms. 


Rms. 


8 


2.54 


2. 296 


2,2!7 


7 


1.808 


1,0811 


1,132 


6 


1.451 


756 


7.57 


.V/j 


1.217 


542 


.5:^2 


5 


1.(.95 


."JOLe 


453.2 


4 


.9149 


829.2 


297.5 


3 


.7988 


210.0 


193 


2 


.714G 


138.6 


122 


1 


.6006 


94.8 


80.6 





.5169 


72.3 


66.8 



The iliiTcciiicul Ix'twt'cii the ohscrvcd mid ('(iiii|)iit('(l Hows 
is not as (.'loso as could Ix' wislicd hul when it is observed 
that tlie How of ail", fVoiii wliieli tlic diauielei's were com- 
puted, was not iiieasurcd tliroiii>li the same sample as 'the 
one tliroiigli whieli the llow of walcr was measured, that 
the pieces of a]i])ai'atiis were not 'tlie same and that the How 
varies theorcticallv, as the squares of the diaiiK'ters of the 
soil i>'raiiis, it must he coiu'cded thai there is iiiiudi more 
tliaii a chance aiii\eiiient. 

The samples of sand used in these trials are repri'seiited 
full size in Fio-. <»(;. 

331. Relation of Observed Flow to Diameter of Soil 
Grains. — If tlic s(inares (d' the diaiiieters of the sand j;rains 
represented in I^'io. <)(; are plotted as abscissas and the ob- 
served and com})ute(l Hows as ordinates their relations will 
be as shown in Fii>-. 95, where it is clear that the rates are 
such as to agree reasonably well with the sipiares of the 
diameters of the <>-rains. 



332. Relation of Pressure to Flow Through Sands.— Most 

experinienters aloii^,' this line haxc found that wliile 'there 
is a general teiidencv for the tlcnv 'to increase directly as the 
pressure there arc^ nevertheless conditions wliitdi prevent 



267 



tlR'sie relations l)(.'iii^' realized in exj)eriiiieiit, in mjino cases 

the flow being' systematically too fast and in others too slow. 

A series of .ibservations by Wclitschkoivvsky and Wollny 



; 




25cm. 






- 500 CC. 




/' 






-4-00 


♦ / 






50cm 


-300 


♦ / 




^ 




-200 


7 y^ 




^ 


^75cm 
lOOcm 


-100 / 


z^^::^^^ 








(^'ffTi, , 


50 75 lOO 125 

., 1 .... 1 ... 1 1 ... 1 . . 


150 

. . 1 . . . 


\75 

. 1 , . 


200 cm. 

, . 1 . , , .1 



^ 





Fig. 97.— Slidwiii;;- .iiiicii-.ii ns (if Wclitschkovvsky mihI the rchilioTi .if pn-s- 
snic t<i llnw ,if wMtcr olisorvcd by liiiii. 

and the aj)))aratns witli wliicdi they were secnred are repre- 
sented in Fig. 97. It will be observed that where the eol- 

nmns of sand iis(>d bv AVelitsclikowskv were 25 :\ m. and 



2G8 



50 c. III. loiii;' tlic llow iiici'cascd laslcr lliaii llic jircssuve ; 
Lilt wlien the colniini was 75 c. lu. long the flow increased 
directly as the ])ressiirc, wliilc when it was made 100 c. m. 
loiig tlieii the ildw did iml increase as rapidly as llic [)ress- 
nre. 



- ' 1 


' — r 


• [ 


■too 


1 




17 




ilOO 


n — ' 
• 3 


lOOOcm 


-1600 cc 
















. 






-liOO 














• 




^ 


^2> 


-800 










' 




^ 


.2 






- 












« 




^ii , 




. -S'S 


- tOOCC 














<^ 


• ' ' ' 




^*3 


- 






rV^^ 


■ 






— 









^^ 


^ 


^-^ 



















Fio. 9S.— Shdwiiiu- II W 

tlu'oli!.'.!! ;;:iiiilsl(iiH'. 



•veil rcliilioii 111' iHTssun' Ic llow cf water 
iiic':isiii-imI in llic ,i|i|ki ral lis uf \'"]'^. li'J. 



333. Relation of Pressure to Flow Through Sandstone. — 
AVluiii. the ilow of water is mrasiiriMl itlir(Mii;h sandstones 
such as constitute most water-lx'aring l)eds it is often tnund 
tliat here, Jis in the sands, the How may inci-ease in a niiudi 
liig'hcr ratio than the prckssure. Three series of sncdi obser- 
vations are ])lotted in V'\iX. OS, and Ihc apparatns used is 
showji in Fig. 1)1>. 

Whore the flow does not increase as rapidly as 1 he pres- 
sure the departure from Ihe theoretical llow has Keen ex- 
plained hy aasuming thai llie^ cni'rents heiMmie turlinient 
and tlnis rednco the disehai'gcs hnt no satisfactory reason 
has yet hcen assigned to the cases where tlie thnv increases 
fas.ter than the i»ressure. 



334. Observed Rates of Flow of Water Through Sands and 
Sandstones. — ''I'he ohserxcd ratcvS of flow of water through 
the series of sands rej)resented in Fig. i^O, when expressed 



200 



ill ciiltic feet per iiiiiiiilc per s(|ii;irc U><>\ of section ;iih1 per 
foot: of Iciin'tli, iiikIci- ;i ,ii,rii(li('iit of I in 10, is f>ivcn below: 

No. « 7 6 5!4 5 4 :i 2 1 

Cu. ft. per min. 5.23 3.65 1.85 1.30 122 .82 .51 .33 .23 .18 




Fhj. 99.— ApparntilH for iiicMsniiii;: Ilif llnw d' \v;iicr 1lir(Mi;;li s;in<is(i>iii'.s, 
uiidcr (inicrciil kimwii |)i-cs.sMrc>. 



AccordiMg to Diii'cv'.s hiw, if tlicsc siiii<l coliinin.s had their 
lengths increased 10, 100 and 1,000 times irhc discharges 
observed would he <»nly iV, I'.d and \»\u> of those given. 
In the case of fonr sandstones the rales of flow were so slow 
that 10 (lavs were i'e<|nii'ed foi- ..!!», .;54, 2.45 and .14 cubic 



270 

ieH. of water to be (lischargcd luidcr the coiKlitious for the 
Hand. 

335. General Movement of Ground Water Across Wide 
Areas. — Tlic: waters whicdi supply aitcsiaii wells and many 
springs, where the discharges take phice through openings 
in overlying impervious beds, are often obliged to travel 
long distances, even 100 or more miles, before reaching 
their outlets. But this cannot occur with such low rates of 
flow as those observed in (234j and it is clear that nearly 
the whole movement across long distances must take place 
ithrough rock fissures and along bedding planes, the water 
seeping out of the rock into tlu^e as it does into river chan- 
nels and lines of tile drains. 



336. Fluctuations in the Rate of Flow of Ground Water. 

When arrangements are made to automatically record the 
rate of diseiiarge of water from s]>rings, artesian wells or 
lines of tile drains it is seen tliat the tl(nv is not uniform, 
varying not only with the season, Init often daily and even 
hourly. 




Fl(!. 100.— Showiiif;- o1is.tv.m1 l>;ir.iiii.'(i-i.' cliMimcs in tlu- nitc ,it' fl.iw (if 
water I'rom a spring, an.l tli.' jippjir.i t ns f.ir rccinliiifr it. l..iwfr .-iirve 
record of sprinjr. 

In Fig. 100 is shown an autographic record of the dis- 
charge of water from a spiing during 13 days, together with 
the changes in barometric pressure as recorded by a baro- 
graph 45 miles t^. the west of the spring. The method of 



271 



reeurtliiig' 'the cliaiiiijCs is also re})r('8('nte(l in the saiiu' tiiiiire. 
The clianges in the rate of discharge from the spring, which 
are associated with changes in the pressure of the atmos- 
phere, amount to as much as 8 per cent, of the total nor- 
mal flow. 




tlif li;ii-ciiH('ti'ic chniijics in llic r;\t< 
tile ilraiiis. Lower <nirvt', drain. 



■page into 



337. Barometric Changes in the Discharge of Water from 
Tile Drains. — Using the same means for recording the rate 
(tf discdiargt^ of waiter from tile drains it Avas shown that 
changes occur here which are entirely analogous to those re- 
corded from the spring, and Fig. 101 shows a week's record 
of the changes both in atmospheric pressure and in the rate 
of discharge from a system of tile drains. In this system 
changes in the rate of flow as great as 15 per cent, of the 
mean have been recorded, entirely independent of rainfall 
and apparently due solely to changes in atmospheric pres- 
sure. 

338. Diurnal Changes in the 



h/4- Bm4 e>'''-' /I f^ * a/zf-f T, 

TTTT 1 1 1 l-m-^- 




m 



J 






^f^^ffl 



B 



£^. 



Rate of Discharge from Tile 

Drains. — Besides the changes as- 

--j sociated with changes of baro- 

HM I / I I \^\y ] r ~~~ nietric pressure referred to in 

t~2Z^Jz2-\Z^lIiU2M (237) there may also be diurnal 

changes in the rate of discharge 

which are due to the diurnal 

71 1 I / I 'LU-^^t^id^l I I I I I f'li^i^i^.'P^ which take place in the 
-^Hm^I m flTTrl I I I I I I soil air above the ground water. 

As the air expands under the heat 

reJii^sci^^edSichanS^in al>sorl)ed it prcsses dowirward 
welistue'^J'^chlnies Z'soCi ^^^n the watcr, causiug it to drain 
temperature. awav fastcr, whicli niakcs it 



272 



iimcli ;is it :i rjiiii luid (•cciin'cd :iii(l |>('rco|;ii i(»ii li;i<I iii- 
crc'as('(| I lie liiiilil of ihc iirouiid wnlcr ilsclf. l^'ig. J02 
hIiowvs llic cliiiii^cs ;\lii('li (lid dcciir in llic lc\-cl of tli(^ water 
in surt'iicc wells near the svstciii ol' lilc drains in (|UC'Htiou. 
Tlic (Mii'\'cs were j)r()(luc('d nl tlic same time \)y sclf-record- 
h\'j; insi niinents. Fi^'. 1 (>''! shows aiiol lier series of diurnal 
fluetnalions where the ehanncs in level were measured 
twice dailv, in the niorninji,' and at niiilit, and Fig'. 104 
shows the conditions under which these changes occurred. 
The lower cni've represents the changes in the inner well 
M'hile the upper cni'Nc shows those in the outer well where 
the water ])erc(>lated from above the stratum of claj under 
the intluence of the air pressure caused by the diuriuil 
changes in temperature. 




ti(i. 10;i.-Mu,wiii« (lull tKilclianKcs 111 tlio Fid. IU4. Sliowing the soil con- 
leviilof the KmuiKi \vat(n- lueasiuod twice ditioiis under which the chanKOs 
daily in surface woUs. „f Fig. 108 took place. 



339. Fluctuations in the Level of Water in Wells.— In all 

(U'dinarv wells, wluther tlic\- are deep or shallow, the water 
is seldom at rest, tire surface continually either I'ising or 
falling througli varving distances, and Fig. lO,"* is a record 
(done such series (d'changes which it will be seen a I'e nearly 



Wednesday NQ)ursday f^fiday 

10 12 2 4- 6 8 10 M ^ f/f a\o 12 2 4 6 8 /O M 2 4- ^f\j<f/^\Z 4 6 6 '0 M2* 

mmimm 


1 
3 


B 


^ 

^ 






U 


I 


TfLl' 




1 


fi 


1 


_ 


h 


^ 


ta 


= 




= 


E 


1 


- 




_ 




1 


i 


E 


— : 


- 








] — 


' — 


1 — Tl 


E 


p 






^ 




^E 




E 


E 


E 


E 


E 


E 




E 






E 


— ; 


2 


se 


p:- 






E 


a 


"1 


E 


^~H 








— t— 


2 


F 


^ 


= 


P 


=- 


-J 


F 


Fi 


1 


1 


w 




— 1 


i 


^ 


tt 






^ 


i 




1 


m 


* 


— 


i 


l\m\\\\\\\m\\\\\\\\\\\\m 




«• 










—^ 






■~* 


ti' 


tt 










— ^ 


— ^ 


— ^ 


re- 


^ 


— ^ 




— ^ 








— ^ 


*-" 



'|i:. 1(1"). ShdwiiiL;- lliid ii.-il ions in Ihc IcM'l of \\:ilcr in ii well :inil sinnil 
l:iin'(Mis llui'l n:il idiis in llic i-mIc cif <liscliiii-nc Iron] .-i sprin;; li.iH' .-i imli 
(lisl.-inl. 




'■■":■ l"ii- Slinwin- snililcn :in(l \:n-^f lliiri im il(,iis in llic level of \v;iler 
ill ii well, (Inrin;; limes of lliniKler slioueis. ilne li. sndilen eliiin>,'es in 
pressure. 



274 



(•(liiicitlciil ill |ili;isi' willi (liosc wliicli (icciincd in llic dis- 
('hiii'^'c (»l Wilier Irniii ;i spniii;'. ( 'li;iiii;cs iiiiicli iiioic xio- 
Iciit lliiiM t licsc iiiid (il slioitcr <liii'iil i(»ii jh'c slmwii in \'\iX. 
MX). h'liict iiiit ions like llicsc ((cciir ;il limes of \iulenl, 
lliiiiider slorins mid :irc <liie Id cIimiiucs in air pressure and 
nol li() rainfall. In lliis <*ase llie <-lianii('s occurred in ii 
drilled well (•() feel (lee|) willi (1 inch sicel <'Jisili^' to I'ock 
and I lie clianiics in I lie IcncI of I lie water were so ureal, tliilt 
(lie iiisl rnineiil had lo he sel oNcr lliree limes |o kee|) llio 
|M'n on I lie r< cord shed. 



'1 i i) 



ciiArTEu xiir. 



FARM WELLS. 



340. Essential Features of a Good Well. — The essential 
features of a ^ood well are : (1) Aiii2)le eapaeity to supply 
pure, clear, cold w.iter. ( 2 ) A location which renders it not 
likely to bo C()iitaiiiiii;it('(| by seepage from surface inipuri- 
tic:S. (3) A casin<>,' or curbing which is vermin ])roof at 
the to]) and if ixwsihle \vater-pi'(K>f in its upper JO lo 20 f(«t. 

341. The Capacity of a Well. —The capacity of a well 
should alwitys, if possible, be much gi'(>ater than the prob- 
able dctuands wliicli will be put upon it, and it should not 
b(^ jxissiblc in a few lidurs lo pump il Avy witji an ordinary 
puni]>. 

In working tlu^ ordinary domestic |)um]) about 20 strokes 
are uuule per minuter and theise will till a |)ail with 20 to 24 
p<Min(ls; this is at the i-ate of about a cubic foot or T.T) gal- 
lons in ;; uiiuutv's and a good wiell should be able lo supplv 
water at this rate for several liours without failing. 

'I lie douicstic ;;uinials on (lie farm will need w.iler at tlu^ 
rate of more ratliei- than less tliiau a cubic toot per each 
1,000 lbs. of weight i)er (lay. A cow gi\iug a heavy flow of 
milk often takes nearly 2 c\d)ic feet (d' water in 24 hours. 

Five cows, during 120 days in winter, averaged ST). 4 lbs. 
per head when the water was warm and 77..'> lbs. wlien it 
was cold. At this rate the eipiivalent of 40 adult cows 
M'ould need ;;,4ir> lbs. of water or .■)4.7 cul)ic feet and this 
Av<»u]d re(piii-e, at the rate assumed above for pumping, 2 
hours and 4.") minutes to supply tliem. 



270 

342. Geological Conditions Which Give the Best Wells 

"J'lici hiriicsl iiiid Ix'st. supplies of well wnlci- jirc iisii;illv touiul 
in tli(^ cxtcusivci SiUidstoiU' foniKil ions mid wlicrcNcr tlicsi! 
arc witliiii ciisy rciu-li the well sliduld Uc sunk iiilo tlicui 
(lec|> cuoiiuli l(» li;i\(' iM) (ir iiku'c feel dl pcrcohit ini; sand- 
stone: suri'iU'c. Next to t lie saiidsloiic I'onnalions as sources 
of water su))ply stand llie liss\ii'ed linu'stones which either 
ov(M-lie sandst(,iu\s or ai-e S(» i-ehited lo the surface soil that 
water Ironi the;n can pei'coiate doA'u iiiito the lissures and 
tliroui;li llieui reach the v\'ell when suid< so as lo connect 
Wi'tli a sv-teni of these lissnres. 

Ai^ain heds of sand hetwec n heds ot' (dav often uive lari;t? 
supplies (d' pure cold water. 

In nianv localities artesian or llonini;- wvlls can he se- 
cure(l and some id' the conditions under which these orii^'i- 
uateare re prescnicd in ViiX. 1(>7. 

343. Conditions which Influence the Capacity of a Well. — 

The rale at which watei- can enter a well depends upon five 
})riine factors: ( 1 ) The size of the grains of the water- 
bearing- heds and the pore space. (i2) The depth of the 
well in the watcr-heariui;' bed. (o) T\\v auiouut the water 
is lowered in tlu^ well when piinipiiii>'. (4) Tlu^ diameter 
of the W(dl. (.">) Whether the well is in or near a system 
of fissures. 

344. Influence of Size of Grains and Pore Space on the 
Capacity of the Well. — JMoni the fact that the How (d" water 
tlirouiih sands is nearly ])roi)ortional to the stpuires of the 
dianivters of the scdl urains, and is i^reatiM- tlu* larger the 
pore space, it is (dear that these are \'er\- inipoi'tant factors 
in deterniiniui;' die capacity of wells. It has heen conipiitC'd 
that when all other factors are the same the ca])acities of 
two wcdls, ill sands haviui*- the diameter of grains of .15 
mm. and .25 mm. and pore s])ac(>s of 'M) ])er cent, and 32 
per cent., are to each other as 5.2.")4 to IS. 01 or one is over 
tlire(> times the other. It is thcrefon^ (dc-^ir that when the 
sand grains and ])orc' space are small th(» other wcdl factors 
must he made enough larger to compensate. 



277 








8- Krillrllanilr 



Fic. 107. — Sliowiii).^ ;,'cii|r)j,'ii-:il I'niiilil inns iiuili'i- wliiih nriosljiii wi'll.s are 

Ji.niMMl. 

17 



278 

The caj^acity of a G-incli well sunk 100 feet into sand- 
stone having different sizes of sand grains but with uni- 
form pore s^^ace of 32 per cent, and a temperature of 50° 
F. give computed flows under a joressure of four feet as 
follows : 





Size of grains in m. m. 








Cu. ft. per mill 


.02 .04 .06 .08 .1 


.2 


.4 


.6 


.047 .189 .580 .-757 1.C8} 


4.73 


18.93 


57.96 



345. Influence of Depth on the Capacity of a WelL — When 

other conditions are the same the greater the depth of a 
well in the water-bearing beds the greater will be is capac- 
ity because this increases the area of the section of the 
sand or sandstone through which the water mav enter the 
well. 

If a ()-inch well is sunk just to the surface of a water- 
bearing bed the area through which the water can enter it is 
only 28.27 square inches. So, too, if a G-inch well casing 
ends in a water-bearing sand only so much water can enter 
this well as can flow through a circle of sand G incheis in 
diameter. 

If the well penetrates the Avater-bearing bed one foot so 
that water can enter the sides as freely as it enters the bot- 
tom then the percolation surface will be increased to 

28.27 -f 226.2 = 25i.47 sq. in. 

making the section of flow nine times as great. Leaving 
the lK)tt(Hn of the well out of consideration it is clear that 
doubling the depth of the well in the water-bearing beds 
doubles the area for water to ent(M* and hence it is a matter 
of the greatest impoi'tance to secure a sufficiently large per- 
colating surface in the water-bearing beds. This capacity 
increases in a somewhat slower ratio than the depth, as in- 
dicated in the table below-. 



279 



Table showing tlie flow in a 6-inch well sunk different depths 
into WO feet of loatcr-beai'ing sandstone ivhere tli epore space 
is 3:3 per cent, and the diameter of Ihe grains .25 m. m. 



Flow in cubic feet per 
minute 


Depth of well in feet. 


4. 


8. 


12. 


16. 


20. 


40. 


8('. 


100. 


200. 


1.003 


1.818 


2.544 


3.265 


4.08 


7.68 


14.88 


18.49 


36.02 



346. Influence of Pressure on the Capacity of a Well. — 

Since the fx()^v of water through sands and sandstone is some- 
wliat nearly proportional to the effective pressure it is clear 
that the de])th of water in the well at low water stage should 
be great enough to permit its surface 'to be lowered until the 
needed pressure to force the water into the well is der 
veloped. 

If, in pumping, the wiatcr in a well is lowered -i feet the 
pressure developed will be about that of four feet of water 
and to lower it 8, 12, 1() or 20 feet \Vill increase the pres- 
sure 2, 3, 4 and 5-fold. This relation being true it is clear 
that not only sliould tliere be an ample depth of water in the 
well but the cylinder of the pump should be so placed as to 
enable the full dcjtth to be lutilized. 

In the ease of a H-inch well sunk 100 feet into water- 
bearing sandstone 200 feet thick having a pore space of 32 
per cent, and diameter of grains of .25 nun. ithe capacity 
of the well under different pressures is computed to be as 
follows : 

Amount the water is lowered in the well in pumping. 



Cu. ft. per minute 


1 
1.8483 


2 
3.6966 


4 

7.3932 


8 
14.7864 


12 
22.1796 


16 

29.5728 


20 
36.966 



347. Influence of the Diameter of the Well on its Ca- 
pacity. — Tlie capacity of wells when they extend any con- 
siderable de])th into the water-bearing l^eds does not in- 
crease as rapidly with increase of diameter as might be ex- 



280 



pected, and Slicliiter computes that three wells 2 inches, 6 
inches and 12 inches in diameter respectively, if sunk 100 
feet into a bed of sandstone having sand grains ,25 mm. in 
diameter and a pore space of 32 per cent, will have capaci- 
ties in cubic feet per minute as follows, when the water is 
lowered 20 feet: 





Diameter. 
'L iuch. 


Diameter. 
B inch. 


Diameter. 
12 inch. 


Cubic ft. par minute . 


... 31.90 


36.94 


44.45 



These amounts are on the ass^umption that the walls of 
the weJl or casing offer no resistance to the discharge, 
which of course is not true, and the 2-incli well could not 
discharge the amount indicated under the pressure of 20 
feet akhough that amount could enter the well if it were 
removed fast enouoh. 




HARD PAT 




Mi 




Fk; 



108. — Sliows a j;oo(l fonn of sanfl strainer niailc by sawinj^ sh>ts in 
brass tubing. 



It is clear from these results that for most wells there is 
little gained in making them larger in diameter than is 
needed to provide accommodation for the pump. 



281 



348. The Use of Sand Strainers. — Where water must be 
procured in loose sand, especially if it is line, some form of 
sand strainer should be used unless the well is an open one 
and even then a suitable point will often g'reatly increase 
the capacity. 

The dilticulty in getting water rapidly from loose sand 
grows out of its tendency to move with the water, filling up 
the well or the suction pipe or cutting out the valves. Since 
the speciiic gravity of sand is only about 3.65 just as soon 
as a pressure greater than 3 feet is developed to force the 
water out of the sand the sand must mjove with it unless 
there is something to prevent it. 




\ 




Fig. 109.— Showing ordinary sand strainers and nu'tlidd of measuring their 

capaeity. 

The best sand strainer we have seen is represented in Fig, 
108 and is made of heavy brass tubing cut as shown in the 
illustration, the width of the cuts varying for the different 
degrees of fineness of sand. Made of heavy sitock and of 
one kind of metal it is not liable to corrode and clog as with 
the common form represented in Fig. 109. 

349. Capacity of Sand Strainers — The capacity of sand 
strainers varies essentially in the same way as wells of simi- 
lar dimensions would, made in the same kind of material. 
The longer the strainer, the coarser the sand and the greater 
the pressure the larger will be the capacity. 



282 



III l^'iij,'. lOi* is i"c|trcsciit('(l :i iiiclliud used in iiiciisiiriii^' 
tlid (•iij)JU'itv dl' tlii'C'Ci (ioiild S;iii(l Si r;iiui'.|-s, ^\os. 50, SO 
and JM), ciudi IS iiudics loii^', and tlic- tabic below f>'iv('s the 
rcsiijils sci'iii'cd. 



Tdhit; n/ioiriii// tin r<i/< of J/ow lliroiijili three drirc well poiii/a. 



Pressure 


No. SO. 


feet. 


Lbs. per niiii. 


2 


6.li 


4 


i:j.2 


6 


lil.H 


8 


;;(•.,. 1 


]0 


:);!.() 


12 


;w.t; 


14 


46. li 


16 


52., s 


18 


r.9.4 


20 


00.0 



No. BO. 
Lbs. per niin. 



2.2 
4 4 

6.0 
8.8 
11 

i:j.2 

15.4 
17.0 
19.8 
2i.O 



No. 90 
Lbs, per rain. 



..57 
1.14 

1.72 
2.29 
2. HO 
■AAA 
4.00 
4.58 
5.15 
5.72 



'rii(> sand abont the No. .")() sfi-aiiur liad a diauuMci' of 
.2!» I iiiiii., illial aboiil llic Xn. SO. 172 iiiiii., and about t ho 
No. !H) .OS,') niiii. 'riic lablc sliows under tliesc eoiidilions 
about. 2 niinnles (d' steady How, under a pressure; (d" 12 i"(H't, 
are re(|nired for the Xo. .M) strainei- to snp|)lv sidlicicnt 
water lor a, sin<;ie cow one dav; (I niinuilcs lor the No. 80 
and more than 20 ininnte'S For the No. UO strainer. 

Il wlonid ill 'ludore be iiccessai'\ to use a strainer .^ 1: 
iiudies loiiji' in 'the Xo. SO <and and one 17 feet loni; in the 
No. !M) sand to snppiv the waler oblained ihron^h the No. 
1)0 st I'ainei*. 



350. Capacity of a Pump on a Sand Point and on an Open 
Suction Pipe. When an ordinary pnni]) is connected up in 
the inanner represented in Fia,'. I 10, so as to draw Avator 
11ironi;ii the sand |»oiiit or tliroiii;li the o|)en suction, tlu,' 
capacity (d ihc pninp under the t w'o coiidilions may be 
\'cry dilVei-eiil. In the case of :i luonnd a half inch cyliiidor 
working- on an IS inch No, ."»() sand strainer, or on tiicopeii 
suction pi|)e as reivrrtscnled in ihe illustration, wheu 20 
t-'trokes would lill the jtail from theopcn suction it re<[uire(l 



28;} 



niisc 



do lli(< 
('.lie to 



nine innoiiiit of 
work was rtiiich 
he Ciici. tliilt tlio 




'.')'}, made at tin* same rate, t 
watci-, aii(i t lie ciici-uv rc(iiii i'c(| I 
i«rcatcr. Tlic iiicrcascil lahor w'a 
water caiiic in too slowlv tlii'oiia,li tlic sand point, to lill \\n- 
.-^pace hcliiiid llic i)iston as rapidly as \i was raised ami a 
\aemiin was formed; into this the i)islon f('ll wlieii tlic pres- 
sures M'as rolcaacd and tlu; 
Avatci' for oidy aliout lialf a 
stroke could l)e SecureiL 

Sand strainers ^ivv. a fair 
well in very coarsen inatci-ial 
Avliore one of sufficient size 
can 1)0 placed in a water- 
l)earin<>,' l)ed id' stdlieient 
tliiekness,l>ut <i('nerally tliey 
can he depended upon for 
only snnill ainonnts of 
"water. Vov wind-mill ser- 
vice they ar(' less satisfac- 
tory heeanse of the lireatcr 
|)owei' re(piire(l to woi'k the; 
jinnip. 

351. Depth of the Well.— 
An important feature; of 
every wcdl, where the water 
is intended for domestic! oi' 
stock use, is a ftuflicieid, 
depth to prevent the (piick 
entrance of water from tlu; 
surface and to maintain a 
constant low temperature. 
This depth sliould usually 
exceed 20 feet and even 
where water is found nearer 
the surface than this it is 
hetter, if the water-h(!arin^ 

» 1 ■n •, /• "i J. Fit; 110. iSliowiiit,' iiK^lli 

beds M'lll ])ermit Ot it, to ^O ,1^, „„„Hcit.v of « pu.np workii.is' on 

30 or more feet and then 



T 






V. 



I of u(>Mir)ariiii7 
working 
gaud HtraifKU' and ou an open woll. 



284 

])l;icc tlic! [)iijiij) so as to draw i\w. water from thv. bottom 
wluvro it is coolest and freshest. 

JJotli de|)tli of soil, to act as a Hlter, and time to bring- 
about eliimi;('s in surliice waters, to free them IVom organic 
mnttc^r, :ire re(|uire(l in order to render tlie watei- t'nllin^j,' 
li|)oii the i;roiiii(| |Mirc ;ind siiit:d)le lo drink. 

352. Temperature of Well Water. — Tlie zone of lowest 
i>'r<»iiiHl teniiperatnre is _i>-enei-all_v fi-om '20 to 70 I'eet below 
tlu^ surtiiiee and in this zonc^ the coldest waters are pro- 
eured., Alxn-i^ :,'() feet. Ilie walei-s will be colder in w^inter 
and warniei" in, .^nninier and below 7<> to ~^> I'eet ilie water 
i^cnerallv becomes warmer from llie internal lu il of llie 
earth. 

'The normal lemperalnre of tlie coldest well v\aler in a 

locality is nsnall\' from 2 to 4 dei;rees liii;iier than tlie inran 

. annual aii- temperature of the place, and in Wis^'onsiu this 

rang'os from 4-'^^ in the norlliern portion to abont 50° in 

the sont liern port ion. 

353. Well Casing- or Curbing-. iM-erytliini; consi<lered 
there is probably nothiui;' beittei' for a. curbing' or casing for 
a AV(41 than, the (! \\\r\\ lap-W(4(l steam pipe. Plie same |>ipe 
g"al\'ani/,e(l is lu'tter because it. will not rust out so ipiickly. 
The great advantage of this kind of casing is that it is --.o 
(*()mi)letely watiM- tight and at the top can be so securely 
closed as to |»re\'ent insects and Ncrndn tailing in. 

Next tO' tiiei ste(4 casing is one made (d' cement tile or 
glazed sewer iilo; with their joints set in cement. Where a 
vv(dl is to have a bri(4<: oi* stonie curbing the u|)per 10 feet 
should bei laid in cenu'nt and plastered with the sanu' on tlie 
back to excdnde surface water and \'crmin. 

354. Top of the Well. — in linishing a well the casing 
should be cai-ried 1 1} lo IS iiudies abo\'e the surronnding 
sni'face and then earth be i;i-aded up to it so as to secure |)er- 
fcct and quick removal of all surface water. 



285 

When' ;i steel Ciisiiia," is used the well |)l;ij t'onii is best 
iiijulo by serewin^' ii wide Haii^e on the iop and then bolting 
tlic piun))h(>a(i <lii'(X'.tly to this, liaving first drilled, holed 
through both to receive the bolts. 'I'liis arrangement seoures 
a very solid and perfectly tight, platform. A.i'onnd this 
plank may be laid, or bettor still, a block of cement. 



286 



CHAPTER XIV. 
PRINCIPLES OF FARM DRAINAGE. 

Both irrigation and drainage are usually looked upon as 
arts whose application to agriculture are required only in 
special cases; but a broader and more helpful conception is 
tiiat all fertile fields must be bdtli well irrigated niid thor- 
oughly drained. 

It is true tlimt ovei- nnudi the larger portion of the earth's 
surface the water re(piired for the growth of crops is sup- 
plied by the natural rainfall, and Avlien this is timely and 
sufficient fit is the best and ide;d irrigiition, done by nature's 
hand. 

It is again foi'tunately true that uiost land areas have ac- 
quired sucdi surfac(>i features that the excess of rainfall is 
opportiuu'ly removed by })ere(dation and seepage or surface 
flow; and this is nature's metluxl <d" land drainage. 

The fundamental fact is that all lands must be irrigated 
or wat<'r(Ml and drained and in special cases nature's efforts 
need to be sui)|)lenu'nted. 

355. Necessity for Drainage. — There are several impera- 
tive demands for the drainage of farm lands: 

1. The removal of the mor(>' soluble salts formed by the 
decay of rock and organic matters, because when the soil 
water becomes too strong in soluble salts it either poisons 
the plant or renders the root hairs inactive by causing the-m 
to shrivel. If these soluble salts which plants cannot use 
are not removed the soil comes into the condition known 
as alkali lands, upon which little vegetation can grow. 

2. Tlie water in the soil needs to bo frequently changed 
or replaced by a. fresh supply containing an abundance of 



2ST 

atni()s])li('i'i(' o\vi;('n hct'ansc the roots of plants and micro- 
scopic life tend tO' exhaust this suivply. If the soil is not 
drained 'the water in it becomes stagnant in a sense, the 
rains wlii(di fall sini})ly nmning' off the surface, leaving the 
soil water tlie^ same as was there before the rain. 

.'5. Fai-m lands mnst be drained in order to render them 
snfhciently tii'ni to pei'mit the farm ojx'rations. 

4. Soils mnst he di-aine<| in order to ])rovide room for 
soil air. (238.) (251.) 

5. The excess of water must be removed to ])ennit the 
soil to become Avarm enough for plant growth. (268.) 
(271.) 

356. Conditions which Require Drainage. — The cases in 
which it becomes desirable to sui)])lement natural drainage 
fall into five classes: 

1. ( 'om])arativel y Hat lands oi- basins npon whicli the 
water from the surrounding higher lands collect. 

2. Areas adjacent to higher lands where t\\v structure is 
such as to ])ermit the watei- which sinks into the high land 
to flow or seep under and up thi-ough tlie low ground, 
making them welt. 

3. Lands inundated regularly by the I'ise of 'tides or fre- 
quently by the ovei-flow of rivei*s. 

4. Extremely flat lands in wide areas which are under- 
laid near the .surface by a thick, close, nearly impervious 
stratum of clay, such as were formerly old lake bottoms. 

5. Lands like rice-fields, water-meadows and cranberry 
marshes where water is aj>])lied in excessive (piantities at 
stated tini(\s and must he removed again quickly. 

357. Deep Drainage Increases Root Room. — ISTo plant can 
utilize the resources of the soil to the^ Ix^st advantage unless 
there is ])rovided for it an abundance of root room. In all 
well drained soils the roots of most cultivated crops spread 
themselves widely and to a de])tli of 2.5 to 4 or more feet. 
When conditions are such as to permit crops to do this the 
best growth and lai-gesit yields result. 



288 

Proper drainage so lowers the ground water surface that 
roots are able to penetrate to their normal depth, and Fig. 
Ill shows how the roots of corn have been massed together 
near the surface because of too much waiter in the soil be- 
low, and Fig. 45, p. 148, shows the apparatus with the corn 
growing in it. 

358. Drainage Increases the Available Moisture. — When 

the roots of a cro]) are forced to (U'vclop so close to the sur- 
face as shown in (357) the first effect is to exhaust the soil 
of its moisture so much as to leave it too diy and so lessen 
the capillary rise that, although there is an abundance of 
water in the soil below, it cannot be brought to the roots 
and the soil below is too wet to permit the roots to go to 
the moisture. 

On the other hand if the ground water is lowered the 
roots are permitted to advance deeper, making it unneces- 
sary for the water to miove u]) as higli and leaving the soil 
more moist, and so capillary action stronger and capable of 
lifting water higher and faster. (198.) (199.) 

359. Soil Made Warmer by Drainage. — Whenever soils 
are kept continuously wet, so that large amounts of water 
evaporate from their surfaces, the temperature is low. Two 
thermometei-s having their bulbs side by side, one left naked 
and the other covered with a close fitting layer of wet mus- 
lin, will often show temperatures as much as 20° different, 
the wet one colder, made so by the evaporation of water. 
The teakettle on the stovei has the temperature of its bottom 
held constantly near 212° by the evajioration of the boil- 
ing water, sho'wing the cooling power of w^ater when evapo- 
rating. 

During early spring differences in soil temperature at the 
surface, due to differences in drainage, may often be as 
great as 12°. 

Tlie differences in the amount of moisture in clayey and 
sandy soil often cause a diff'erence of 7° F., in the surface 



280 




Kiii. 111.— SlKiwiiiK' linw llic nulls if <■<<{■][ ;n-i' fm-ccil Id ilcvcldii near the 
siirfiLiM' \\li('n tile soil is hkI dr.-iiiicil. Set' aiiparatiis. I'"ii;. Ifi. \>. 148. 



290 

Iddt, when Itdtli arc well diniiicd, and :is iiiiicli ns ."> in the 
ScxmuhI :iii(I I liird feet. 

360. Soil Better Ventilated by Drainage. 'I'lic cliaiio'c of 

air ill wi I soils allcr llicv have Itccii well drained is very 
iiiiudi iiioic- i| lioroiiiili and this is perhaps I lie i;r,-|l('sl henc- 
iit. due to drai iiai;c 

Tlierc^ are several wavs in wliiidi I lioroiii;li drainaii'e leads 
lo a more rapid e\(dia!ii;(' of air in tlie soil: 

1. Loweriiii;- llie i;roniid water eiiahles hotli the roots (d 
plants, and aniinals like earthworins and ants, to penetrate 
tliosoil ui()r('(lee|)lv, lea\iiii; passai;('\\avs lari^cr and freer 
tlijiii. existed hefoi^e. 

-. When the (h cper (davs eoine to dry alter heini;' 
drained sliriiikai;e (dieeks are formed in i;reat nnmhers and 
liiroui^'h th(\s(s the air iiioncs more IreeK'. 

'■). W'i'lli tlu'i deeper penetration of soil air nitrates aro 
more t reely lormed, and witli the lariicr amounts if solnhK' 
salts the (day is lloeeMlat( d, makiiij^' a more i;raiinlar text- 
ure, which auaiii admits the air more freely. 

I. When lines of tile are laid under a H(dd :>() to 100 feet 
apart they furnish an opporl unity, with {'vrvy (diaiii;-e in 
atni()S])lierie pressure and (d' soil temperal nre, to force air 
into and out o( the soil, and so a line of tile laid in the soil 
hecoines a system lor air circnlat ion. 

T). With i'Vi'vy liea\y rain wdiicdi causes jtercolat ion, 
where the water can tlow away, a \olnnie of fresh air is 
drawn into t he soil after it, coni|iletely (dianuin^ 'I he air. 

361. Kinds of Drains.- Ther.' are tw(. types of drawings: 
(1 ) (dosed and heiieath the surface after the manner of un- 
derground water channels; and ( iM open, such as (litt'lu"S, 
wdii(di are in fuiudion like natural ri\('r (dianiuds. 

'Idle (do^ed forms ai'c usually iiuvst etl'(vtivo, l(^ast in the 
way, re(piir(v less expense; in maintenance and are nutst 
durable and should generally he adopted, Imt I here are cases 
w here surface ditidies luusif l)e used. 

I n t he earlier history (d" underdrainini;- (dosed drains wero 



291 

made by laying bundles of twigs in the bottom of the ditch 
and covering them, expecting the water to trickle through 
the passageways left. In other cases two or three round 
poles were covered in the l^ottoni of tlie ditch or two slabs 
were laid ('(]*y(' to edge with their i-onnd sides down. 'I'wo 
Iniai'ds were sonietinies set on (Mlgc X'-shaped, with o))cning 
d(nvn. 

Mow |)ci mancnt cIoscmI drains w( i-c nia<lc l>y iilling tl)0 
bo'ttom (jf tlie ditcdi with (•ol)hh'stone, by setting Hat stone 
on edge V-shape, by setting two lines of stone on edge and 
covering with flat stone and eve-n by using four stone for 
top, bottom and sides. In other cases brick wCre used in 
place of svtoiKJ and some even made tile out of blocks of ])eat, 
cutting semi-cylindrical cavities in the faces of square 
blocks of peat, then laying these together to form the water- 
way. Most of 'these devices, however, must be looked upon 
as makeshifts rather than as permanent im])ro\'eiiients, and 
have largely gone out of us(\ 

The modern tile, made of iiai-d bui'ned clay, is cylindrical 
in form and usually in 1-foot lengths with diametei's rang- 
ing from 2 to ] 2 or more incdies. 

362. Essential Features of Drain Tile. — A good drain tile 
should be liai'<l bni'ne(|, gi\'ing a clear ring when struck. 
It is much more important to have them hard burned and 
strong than it is to have them open and ]>orous. Soft 
burned tile wdiich give little or no ring when struck are 
much more liable to crumble down under the action of 
fi-osit. We have visited one ficdd drained with soft burned 
tile laid 2.5 to 3.5 feet deep and, in less than five years after 
laying, holes appeared in the field in many places. On 
digging in these places it was found that the tile had 
crumbled into small chips, caused by freezing. 

Tile are sometimes made from clay containing pebbles 
of limestone which when l)urned are converted into lime. 
These lumps of lime bedded in the tile slack as soon as 
wa;ter enough reaches them and by Iheir expansion the tile 



292 - 

are broken. It will often happen that such tile may be laid 
in place and covered before the slacking occurs. 

Besides being hard bnmed, strong, giving a clear ring 
Avhen strnck and free from lime the tile should be smooth 
and straight, with square cut ends and true circular outline 
so 'that they may be laid with close joints Avhich will ex- 
clude silt. 

363. How Water Enters Tile.— The texture of a tile is like 
that of common brick and will allow water to flow readily 
through the walls, but even were the walls water tight the 
Ayater could still find access to the tile through the joints 
formed by 'the abutting sections as rapidly as it can be 
brought by ordinary soils requiring drainage. 

Measurements made of the rate of percolation through 
2-inch .Tefferson, Wisconsin, tile showed a flow of 8.1 cubic 
feet per 100 feet of leng-th in 24 hours, under a pressure of 
23.5 inches, when surrounded by clear water oidy. When 
the same tile were bedded in a fine clay loam, so that the 
water had to percolate through the soil, the discharge was 
reduced to 1.G2 cubic feet per 24 hours and per 100 feet. 

364. The Use of Collars. — It has sometimes been the 
custom to use collars to slip over the joints formed by the 
meeting of the sections of the 'tile, with the idea of better 
excluding the silt and of holding a better alignment. The 
collars are short sections of a size of the tile larc.e enough 
to slip over tJie joints readily. 

The use of collars is not ad^dsable, first, on account of the 
greater cost, and second, becaiise Avlien good tile are prop- 
erly laid they are not needed. 

365. Depth at which Drains Should be Laid. — It is seldom 
necessary to lower the ground wat( r more than four feet 
below the surface and except in very springy places a depth 
of 3 feet will answer most purposes. 

Since the level of the ground water changes with the 
season and since many lands which are benefited by drain- 



39; 



age ai'c oiilv t(M» wet (hiring tlie s})riiig it may be best 
to lav the (li'aiiis only so cleej) as is needful to bring 
the field into condition for working in due season, 
and in such eas(^s tile ])laced 2.5 to 8 feet, rather than 3.5 
to 4 feet, will usually be found sutticient for general farm 
crops. 

AVlun tile are ])laeed needlessly deep not only is the cost 
greater but, in all of those cases where there is an under- 
floAV of water from the higher land, the level of the ground 
water is drawn down earlier in the season to such a depth 
that the crop will get less advantage by the subirrigation 
resulting from the capillary rise of the underflowing water 
into the root zone. 




Fk;. 112.— Ht-prosentiii}; an apparatus for demonstrating the slope of the 
firoiind water surface back from a tile drain and the changes in 
I)ressure when discharffe is takiiiir place. A. front elevation of tank, 

with a, b, c, d, faucels from drain tile, and 1, 2, 3 15, i)ressure 

gauges: H. li, venical scctKiiis Iciiict liwise, with 1, 2, 3, 4, tile and 
faucets, ;ni<l .5, supply tile at euii: (". cross-section, with 1, 2, tile; 
1). secti(JH ar 1 in P., showing connection of faucet with til<>. 



366. Rise of Ground Water Away from Drainage Outlet. — ■ 
If reference is made to the contour map of the ground 
water surface, Fig. 80, p. 257, it will be easy to compute 
18 



2!)4 



tlio gr;i(li('iil, of the groiiiid water surface as it rises back 
from tlu! lake. In well 2t), 150 feet from the lake, the 
water hUxhI on a certain date 7.214 feet above the level of 
the wat(M' in llic lake, tlins slu)winf>' a mean rise or gradient 
of 1 foot in 2 1.1 feet. J n llu; same locality, but outside the 
area represented by the unip, a well stands 1,250 feet back 
from llic lake and in this the waiei- has a level 52 feet above 
the lake or di'aina_i;(! ontlet, which i;i\'('S a mean g'radient 
or rise of I foot in 2 1. 

in V\}2;. 112 is r(\])resente(l an a|)i)aratus for demonstrat- 
iug the position of the snrface of the <;ro\ind water and the 
dillcrcni'c ol prcssnrc at ditlci'cnl distiinccs awny from and 
above a di-ain tile, and l<'ig'. llo shows the observed differ- 
ences of prcssnrc nn(h'r I wo sets of conditions. 

In l*'ii;'. Ill is also rcprcscntcil the <;('iicral slope? of the 
gronnd wati'r surface and 'llic niodilication (»[ it by a line 




Ji3*'S67BaionJ 


S 13 1* ^* J 


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Fid. US. -Sliowlufj 1h(> cluuiHOM In ]>n'ssur>> ill (UlVcrciit tlisluiic(>s froiii 
(lie lilc ilniiii wlicM llic >\i\t('r is llowiiiK. Tlic lower ciirvo sliows (lie 
in-cssiirt' wlicii (lie (lew Is fi'niii (lie slopcdck n, It'l^'. H'-!. iiiid I lie 
iipiMT set ol' curves reiircsciM cliinifics wliicli ccciirrcil during ii period 
of ll.iw Iroiii llie stopcock ., l<'i).v. 312. 

of inliltration ])ipcs, which is in effcH't a tih^ drain. The 
rate of rise of the grouud water back from a tile drain is 
one of tlu^ chief factors in determining- ihe distance apart 
the drains should be placed in the field. 



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Kic. 114.— 'I'lic tiiipci- imrti'in is ;i (liiif;r:iiii of lliiiiie (if West Los AiiKuIes 
AValcr ( 'oiiipiiiiy .mikI vi'Miiil.v. Niiiiilicrcd^ dots sliow wIiitc Icvt'l of 
;;rouii(l walt-r was iiicasurcii in wells siuiK for the |)iiri)os(', and cor- 
respond Willi iniiiilx'rs on lower part. Lower iiart, jirotiles of the 
surface of the ;iroiind water in tlie ^i(•inil.\■ of the West Los Angeles 
A\''ater ("ompaiiy. 'I'lie lieavll.\' shadiMl line is the f^rouiul water surface. 
Kai-li square represeiils ]()() by 10 feet. 



29G 



367. Distance Between Tile Drains. — Tliero are three 
j)rini(' factors wliicli (Iclci'iiiiiic llic distance between tile 
(li-aiiis. I. 'riic crtVctivc siz(! of soil i>'rains and ])oro space 
of the subsoil tliro.uji>li which the water nnist move to reach 
the drain. Jf the subsoil has u close fine texture the re- 
sistance to the flow will 1)(^ lii-eat, and hence the water sur- 
face will rise fastci- back from the drain, bringing' it near 
the surface sooner mid inakini;' it necessary to place the 
lines (doser togetlier. 

2. The depth at which the di'ains ai'c |)hieed. It is clear, 
that when it is desifed to hold the wat(M' midway betwe<'n 
a line of tile a certain distance below the surface, that the 
(leei)er the 'tile are placed the fui'ther they may be apart, 
and Fig. 1 1.") illustrates both this point and the first. 

'"). 'idle iiiter\;d between lainf'alls sullicientiv heavy to 
])i'o(luce percolation. In regions where the rainfall is both 
hea\-y and frecpient iiles need to be placed nearer together 
than wliei'e the revei'se coinlilioiis exist. 




Fl(!. lir.. Show ih.i; I he inlliiciic.. ,,1' ilKl ;iiic.- hrlwccn file ilr:iiiis on llii- 
rcljilinii ,,( III.' -rdiiiHJ wilier \,< llic siirl'arr .if llic m-.imiil. 

In general piactice for field crops it is usually siiflicient 
to place the lines of tile frdni ,')(» |.. loil fed apart. In 
tav(uable cases tiny may be placed ev< ii fnrlhei- apart than 
this and in special cases tlie\- nia\' be icipiired as (dose as 
;'>() feet. 



368. Observed Ground Water Surface in a Tile Drained 
Field.— in Fig. JKi is represented the observed ground 



AViitcr sui'1;icc in :i t ilc 'I raiiic(| ticM where (li<' lines arc 33 
feet apai't, -'{ to 4 feet Ik'Iow \\n' surface and wlu^re tlu; sub- 
soil at ') to 4 feet and helow is sand. TIk^ slopes of tlic sur- 
face was oKtained hy horinii' wells with a 4-ineh au^cr be- 
tween the lines of 1 i ha iM I I he nieasnrenients were nuide 48 



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I<'i(;. in;. Show ii]^;- ll I)srr\i i| ciiiirdi-niMl ion <>( llic ni-(iiiiiil w:iIit siir- 

f-Ai-i- iij :i lili' iliMiiird I'h'lil IS iHJiirs mI'Iit a |-:'iiir:ill (il' ,X7 ilicli. 

liours after a I'ainfall of .^7 inch May 1-'), when th(! soil 
was already well saturate<l. On tliis dat(! the bi^hcst level 
above the top of .'! inch tile helween any two lines was 1 
foot and the lowest .-'5 foot. 

369. Rate of Change in the Contour of the Ground Water 
Surface Between Lines of Tile. — A I \ he I ime i he daia lor tin; 
la.st se<'tiou were^ taken observations were als(» made to de- 
tennine the rate' of (diaiiiic in 'I he le\'( I (d' 1 he j^round waler 
after the I'ain, an<l Viix- 1 IT repi-esents the (lifferenees in the 
level of the vvalei' al and hetween llie lile drains on llire(! 
different dates, it will he seen thai IIh' water fell faslest 
luidei' the hiii'liest uroiind and on the I'illi wa-^ below the 
'tih' in the upper pari <d' t he lield. 






1 Z } A > (, 7 1 




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Fli;. 117. SliowiiiK '-liiMiKi'S in IIm' level df llic ;;riinii(| walci- surl'.ii-c in 
a lil<- (Iraincil lii'lil. 

This illustration makes it (dear also how the tile in th(! 
lower portion (d' the lield make their inllin-nee lelt in the 



'208 
ii|>|)('r pdilioii, 'llif walcr iii(i\iiii;' :is iii(lic:it('(l hv llic \()\\<^ 

MlTdWS. 

370. Movement of Water where Heavy Clay Soils are 
Underlaid with Sand. — WIk ii :i lic;i\v, close sdil is midcrhiid 
Avitli Siiiid (ii- t;'i"i\'('l llic iii(i\ciiiciil ol watci' towiird tlic lilci 
drjiins will he nliiidsl ciitirrlv 1 lii-()ii_<;li the sand when i\n\ 
(•(Hidit ions arc like those represented in 1^'ii;'. IIS. In such 
en.ses I lie rains |terc(dale \'ei'l icall v down iiilo I lie sainl and 
'then nioN'e latei'allv to tlie tile di'ains, wlieriv it rises to enter 
tlieiui, as shown 1)V the arrows. 






r\N j^— ■ ^ ■— 




h'ni. UN, Shuwihi;- how lln- main Mow ciC walcr Id lines i.l' lilc may l)i,> 
llu'ini;;li a snlisiiil nt' saml when lliis is pri'scnl and near Ilif sui'I'arc. 



It is (deal' I lial under coiid it ions like t liese t he hea\' v (day 
soil al>o\'(* (lo(>s not deterinine the distance apart, drains 
should lie placed luit rather the sand stratum l)(dow. 

371. Fall orGradient forDrains. — (JeneralK' drainsshonhl 
be _i;i\('n as niiKdi fall as I he condit i(tns will permit and 'tho 
_t;,i'adient should not he less than l' iiudies in !(»(> I'eet if this 
can he secured. ( 'ases will occur where less must bo 
acccjvtctl and then car(d'nl le\'(dini;' must be doiu' to sccui'O 
the largest fall a\ailahle. 

It. will olleii happen that the line (»f lowest i;i'onnd is 
(piite toi'tiions, iiiakiiiii,- the distance loiii;', and on this ac- 
(M»nnt niakini;- the fall small. l*'re(puMitl_y in such cases cuts 
a,crc)ss bends can be made by di^iiini;- deeper, in this way iu- 
creasiui;' the fall, as is sometimes done in st raiiihtening 
sti-ea.ms. 

372. Uniform Fall Desirable. — Eil^^ort should ho iiiado to 
.secure lln'onj^liont the couise of a uiain or hitoral drain a 

uiiiform fall, .iiid iieNcr, whei'e it can well he a\'oidod, 



209 



change from a steeper to a less steo]) orade^ because if tliis 
is done there is thiiiiicr that sediiiieirt may lodge where the 
fall is less and close uj) the drain. The case is different 
where a change can be made from a small fall to one which 
is greater, for then whatever sediment is carried by the 
water along -the flatter slope will be carried down the steeper 
one. 



\m}m^^i^<^^^^^\i^^^j\^ ^^ 



J./'z/'S.-i 







Fio. 119.— Showing the construction of a silt basin. 

373. Silt Basin. — In changing from a steeper gradient to 
one which is less the danger of clogging the tile can be re- 
duced by introducing in the line, at the place where the 
change is made, a silt well. Fig. 119, which provides still 
water in which sediment falls and from which it may be re- 
moA-ed as often as necessary. AVhere these silt basins may 
be small glazed sewer tile of suitable size may be used for 
the portion above the ground. 

374. Size of Tile. — Tju- pnjjxM- size of tile can only be de- 
fini'tely stated when the: detailed conditions under which, the 
drain is to work are known, 'i'hey sh(»uld be large enough 
to remove in 24 to 4S hours the (wcess water of the heaviest 
rains likely to occur. 



;;(>o 



1. Wlici'c single (liiiiiis jirc hiid line iiiid llici'c in iii'ci;- 
llhir oi'dcr Id (liiiiii IdW plnrcs liirij,(M- lilc -.we rc(|iiir('(l illiiiii 
where ;i wlnde ireii is svsleiiiiit iciil I v tre;ile(|, liec'iiise in llie 
lornier eiises ;i liir^cr per cenl. of snrfiice wi.ih r IVoni snr- 
]'<iiin(lin^' lii^liei* liimls will llow n|i(Mi I lie low jireiis under 
M lii(di I lie driiius nre laid. 

2. Tlie i;reid(r llie Inll llie snialler llie lile in;iy bo, — 
<l()ld»lini;' llie i;r;ide iiiei'ejisiiii;' llie e:i rrvi iii;' e;i|)iieil_y noni'ly 
one-third. 




Fi(i. 119)1. Appnnil lis to (Iciimhisi nilr llic liilluciiri' ol' liciil, iliaiiicli'r, 
IciiKlli, iiliil IkmhIs cii the imIc .if (Ijscli.i ri;.' of wmI.t Ihiuimli lini's of 
lilc .'Hill wiili'i' |ii|ir. 

<>. 'i'he nrens id" cross seetiim ol lile inerciise with ihe 
squares of I heir dininelers: 

M' tlieir diiiUK'lers are in 1 he r;il io nt" 2, -5, I, .'., •;, 7, their 
anuirt will be; iii the ratio (d" 1, !», Ki, lT), 'M\, 4!», hut as the 



301 

tVictioii on llif walls .if small lllc and tlic (list nrl.anrc dno 
to eddies set np at llie joints are uri aler in pi'opoi't mii to lli(> 
ainolint (d' water eairie(l the capacities of tile, rnnnini;' lull, 
iiu'i-ciise faster llian the s(|nares ni' tlieii' inside diameters. 

1. I't is seldom advisahN to use tile smaller than '■'> intdies 
in diameter because so litl le \ariat ion al)o\-e oi- Ixdow a true 
<;rad(^ will lill t lu'in with sediment. 

■). The size (d' mains niusi varv with the ai'ea tlioy aivto 
drain, with their fall and their leni;th. ( ". (1. Klli<'tt stales 
that where drains are laid ■'! feet uv more deep, and on a 
i-radc not less than :) inches in 100 feet, a 2-incli main not 
mole than .^00 feet lonu' will drain L* aci'es. 

A tliroo inch lil(^ will drain 5 acros. 

A four " ^'^ 

A flvo " " " " ''^" 

A six ' *^ 

A seven " " " " "^ 

lie speciti(s fnriliei' that a i' in(di main slhtuld not he 
laid loni;cr than :>(H) feet and a :; in(di ikH loni;ci' than 1,000 
feet. 

375. A Practical Illustration of Sizes and Distances Apart 
of Drains. — The sizes of mains and suh mains, the sizes of 
laterals, the^ len<;tlis of ea(di size used and the distance be- 
tween drains mav be most (dearly and brieliy slaited by 
(dtin^ a piactical example. The case selected is an SO acre 
Held laid out under t hedirect ion of ('.( i. l<dliott where the 
soil is a rich black loam a])proa(dnnj;- miuds: in its l(»west 
places and at ^iJ* feet undei'laid with a ycdhiw (day subsoil. 
The fall of the main is not less than 2 inches in 100 fcot, 
the laterals beiii^' nun'e ratliei' than less. This area is re]-»re- 
seiited in Fio-. 120. 

The main be.^iins villi 1,000 feet of 7 iiudi tile carryin.i;- 
the water from SO acres of Hat laud suri'ouuded by level 
fi(dds. Next folhtw 1,L^00 feet (d' (i in(di, I hen COO feet of 5 
inch and (dosing' with l;")? feel <d' I iucdi tile into \vlii(di no 
laterals lead. Nothing smaller than :'. intdi tile are used for 



302 



l:il('l'ills ;iii(| I he Ic.'i 

led.. 



ilishiiicc Im'I ween I liciii is iiIkhiI 1 .^O 




l'"l(l. 1-1), liriiliiiiKc s.VHlfiii dl' Nil MITCH. Miuihlf lilies, iiiiiliis; hImkIi- llnrs, 
liili'i'iilH. Nimilii'i'H nl\<' li'ii^jlli mill illaniflri- nl' llli'. (Allrr t '. <;. 
Kllloll. 



376. Outlet or Dniiiis. ,M iicli cure slioiiM lie cNcrciscd in 
sricrl iii'U' llic liic'ilimi Inr, :iiiil in |il;ici iii.',, llic uiillcl. It 
hIioiiM if |)(issil>I<' li;i\r ;i ficc nnll';ill ;is slmwii ;il A, h'ii;'. 
121, I'll t lie I' til ill! In end Ix'iH'iilli Wiitcr ns :it II. 



/f 



^ "f 






-l';.:..i.tMMJ! 



y^y^ 






^. - I 




I \ ■'•) 



li'iij. l::i. .\, |ir(i|irr iiiilli'l I'nr ili-alii; 1!, lin|pni|iii' lullri, i , |m..|>i'i n 
linn III lal'i'iil wllli iiiain; I >, liii|irii|ii'r Juiirllon. 



'Ti* moid iiijiirv I'nnii rr('c/.iii<>' in cold el iiii;ilcs ■! lie |;ist 
H> li> lt'> led (d tlic iiKiin slumld <'iid in i.d;i/.rd sewer jije er 
in llie i-l;i/ed di';iiii lile; :ind llie onllel slieilld l>e ^iiiirded 
willi iiKisoniv iind euvcitMJ with w ^i'ii'l ilii; In Lee|» diit nili- 
inals. 



3o;i 



377. Connecting- Sub-main with Main. Wlicn-M siil» iiwiiii 
joins ii iiiiiiii llic' (•(.iiiircl ion should he iii;i(lo :il iin Jiciito 
iin^lc ns iv|n-csciil('(l at ( !, \^'\^. liil, riiilicr lliiin at rift'lit 
;,i,u|,.s ;is a'l I). I f this is not (lone, silt will ••olhct on ae- 
cinnt (if the ic(lncc(| \clocity canscd hv IIm' nicdini; ol I he 
two sircanis. It is host in sncli cascH, to use tlio niannlac- 
'tui'('(| jnnct ion t ilc 

378. Joining- Laterals with Main. The jnnclion of a 
latci-a! shonld if po.-sihic he iMa<lc alio\c the axis ol the 
main, cnltini;' ;i h<dc liiiwniizh the main with a lilc |)it'k; 
this is to avoid 'the cio.uiiini;- of the lateral. Where the lall 
is ^reat eiiono h jo ;idniil (d' dolni;' so one of I he liesi nniona 
with a main is re|)i-esented in Kig'. J22, tli(! end of tho 
lateral heini; I iH.i'onijhl v |.liig',u'e(l with a slon(^ hcddc*! in 
clay, or hotter with ^I or 1 inches of cemeid,. 




Kki 12L' .Mi'lliod of (■(jiiijccliiiK l:il<'i':il wiHi himIii <Iim1ii. lAfhT .hll. 

Kniiii.) 



Where, on nceonnl (d" -mall fall, the l;itei-al mnst, a|)- 



|)roacli 1 he. main low dow 



II it should lie: coiinecled in tlio 



ohli(|ue manner re|»resenled in I^'i;.';. 1 i^ 1 at (>. 



379. Obstructions to Drains. The d( inand lor water by 
trees is so gicat that they must not l»e |iermitti'd lo ;j,row 
within :5 or I r(Mls .pf a line (d' 'I ile whi.di has wat<a- riinninf^ 
in it durin;^' any (-(Uisideiahh' portion of I he growing' season. 
Fi^. 12'> n.'presenis two iMinelies of Muro|)eaii hirch roots 
tak(ii from (> inch tile whicdi they had complelely (dosed. 
A small r<»ol let entered ;it t he joint ,wlier(! it ft'rew, branched 



304 



iiiid cNiiniidcMl until ils tihrils collcrlcd so iiiiicli silt as to 
coiiiplcitclv close I lie drain. 'I'lie willow, ]>o|»lar, ("liii, larch 
and soft niajdc arc aiuoni;' tlic trees most likelv 'lo make 
tronhle in I liis wa v. 




Fl';. 123.— Udots of l';iir(i|U':iii l.iiili i-cinowd fnnn ;i Ci inch lilc dr.iiii, wliu-U 
(licv luul crrcclniillv cloiAuvcl. 



380. Laying- out Drains. — Careful study slioidd he given 
to the best inanner ol' hiving out a system of drains; i he aim 
being to sin-ure the gi'catest talK the least amount of dig- 
ging, the least (Hit lay f<tr tile and the most pei'fect drainage. 
To secure tli(\se results drains must he laid so that no two 
lines are taking \\n\ wat(^r from the same territory, 'the out- 
l(>ls must he as few as possible and only as large tile used 
as are needt'd to (h* ihe work. 




I''l<i. 12-t. Two sysli'iiis !(ir I.-iyiiif; (uit drjiins. 

Ill I-'ii:. \-2\ (li'iiiiis ;irc hild out by two systems for tho 
Siiiiic area ol' 1 i acres with I he lines 100 feet apart. By 
tlic system A i'>-2:> feel of 1 iiieli main and ;5,0iJ0 feet of 3 
inch laterals are rcciiiired ; while hy tlie system B only 550 
feet (tf 4 inch and 2,S-'50 feet <»f .") inch tile are ro(|nire(l to 
coN'er the liround so as to 
secure cinaldrainaiiv. It '''''' . , '''''^ '' '' ' '''''' 

3 3 

will he seen that in the sys- 
1eni A I h( ■ ends (d' all t he 
laterals I !'a\-ei-se '>() feel of 
territory drained hy the 
}nain. 

When loiii^ I iiies of tile 
must he laid, !'e(|nirinu- 
more than one si/.e, three 
systems ha\c heen used : 
1st, tliat re|)res(iit(>(l at A, 
Fi^. 124; lM, that at A, 
125and :{rd,that at B, 125. 
In the second case, cover- — s* 
iui!,' an area 2,000 feet hv 

i>00 feet, above llie line aa, ''"'- ^^^-'r^o.yst^sU>vh,y infant 

!J,000 feet of 4 inch and 



N 



y„-^ 




S <"..■• 



306 



9,000 feet of ;] iiK'li iHo uiv laid 100 feet apart; Imt follow- 
iiipj tlic third system only 3,000 feet of 4 iiieli and 15,300 
feet of .') iiu'li rcMidcr tlie same service M'itli a saving of 
about $3:5.00 for tile. 

Usnallv no siiii;l(' sy.'-itciii can l»c followcil hiil I lie sl(»|)e 
and slia|t(^ of the land will i'c(|uii'c a citiiihiual ion of two or 
more. 



381. Intercepting Surface Drainage. — hi vcrv nianv cases 
wliei-e drainage is recpiircd the necessity is caused by 

lie collection of surface 
\ate!'s from llie snrfiMind- 
ing higher lands. 1 1 nuiy 
lien be ])ossil)le iii such 
cas(>s to avoid a hirge part 
id" the expense of under- 
drainagc by inti-rcepting 
ind controlling the sur- 
face waters, (collecting 
hem into surface drains 
and leading tlu>m away as 
represented in Yig. 126. 
111 this ease the water is 

Fui. ]26-Motliod.)r intorcoptinsr snrfac><'""*'<'l^^'<^ i"^<> '^ SUrfaCG 
(Iriiiiiajfo. A, B, siirfiico ditcli. cFi-oin,| jf ,,1, lw>f, ,,•(> if- vciches tliP 
Irrifjation and Draiiia^'o.) HIH II 01 roU 11 1 ( .U IK S UK. 

low area and is carried 
around on tlu^ higher ground. It is specially important to 
use this method in cases where low areas are surrounded on 
all sides by a rim of land high enough t(» ])revent the con- 
struction of underdrains. 




382. Construction of Surface Drains.- -Wh(>r(> surface 
"waters arc lo he handled as in (381) it can nsually best be 
done by const nicl iiig broad and coinparal ively shallow 
runways, wliicdi can be kepi in periiianeut gra.SxS, the width 
an:d slope (d" the ditch heiiig such that a W(agon and mower 
c:au readily be driven along and across it. Such waterways 
slu)uld usually be 1 to 2 feet deep and 10 to 15 feet wide 



r,07 



witll .-ides slo|»iii,i;' i;ciill_V 'in ;i ll;i( ImiII(iiii wliicli ciiii carry 
a coii'si(l(M-:iM('V<»luiii(' ol'walcr slowlv -villKml, Immhi'' eroded. 
383. Intercepting the Underflow from Higher Lands. — In 
a verv lai'iic iiiiiiihei- (d' eases lands rei|iiire drainage he- 
cause (d' tlie uudei-llow ni' waler t'roiii the adjacent Idiiiier 
Jand in th(! manner indicated in Yvj;. 1^7. Tu such cases, 




Kl(!. 127.-SlHiwiim li.iw liiirs ..f lilc in:^\ br |ilai-,.,l ,il A ami 1'. lo iiilci-- 
<-,'pl llic iiiHlcrMiiw I'mhii tlic hi^licr ImihI, 

when (h'ains are hiid ahmi;' the Idu't el" tlie hili hehiw t ho 
ground water surface, as I'epresentecl :it A and I!, nnudi ol 
tlio see|)a^c \v'a<ei- will rise into the drain an<l he conveyc^d 
awav rathei- than tlow on umler the ilat land heyoml. When 
such corrections as these are made it may even he unueces- 
sarv to underdi-ain the flat land or when the drains at the 
f,,(,t, of the hill do not fully coi'rect the evil the cos't is 
made relatively less. 

384. Draining Basins Without Outlets. — There frequently 
occur sinks or ponds entirely surrounded by rims too high 
to |)eriint, drainages outlets to he couistructed across them. 
Such cases must he uiet in s])ecial ways. 1. Occasionally 
such basins are underlaid with gravel or sami whicdi is 
well drained and the water is retained on the surfaxte oidy 
l)y a com])aratively thiu stratum (d" clay suhsoil. When this 
is true, one or more wells uiay be suuk through the (day 
into the sand or gravel, as rc-presented in Fig. 128, and 
tilled with cohhlestcme and gravel. Into this underdrains 
may he led from various directions to collect the water 
and bring it to the subterranean outlet thus provided. 

2. Where several acres must, he <lraine<l the above 
method would hardly bo ])racticable even if the under- 
drainage conditions were favorable. It is possible, how- 



:508 



ever, to ;in'iiii,i;c in siicli ;i iiiiimici' tlint a i^uixl \\iii(liiilll 
M'ill drain a considd'ahlc IxmIv of land, where only the 
lindei'How must be (h'ait with and the lilt is h'ss tliaii 20 
foct. One method ol' (h'aininii' l»y wind power is illiistnitcd 
ill Fin'. 12!) wliere A is oiu^ of a iiiindx'r of closed drains 
; ;;[ ' """"" ^ "'" ^"-1,(1 III ■<-^j-j, ^ | (^ , ^ j, n, n. ''^ ■'■ '' j. , j^^J i->''-'-'MiiMk,,iiuijui;»-^ 



*^}^ 



I'll.. l:^N. Mclhoil ,,r (liMiiiiiij; sinks. 

leadin;^' to a coUeetini;- hasiii, I), whicdi is eonneetod with 
th(^ well I rem wliieli the water is dischariicd thi'oui;h tUo, 
pump into t he drain ( '. I I' the area is snndl or the ea|)a('ity 
of the pnnip lari^e the watei' may diseliai'uc direetly into 
(he well, \liieh ma\' he pro\'i<le<l with a lloal t() liii'(i.\' the 




inill out (d" ii'ear when the water is i;('t'tini;' too h)\v loi' th(^ 
|)unip. The ohjeet (d' the well is t() pei'unt the null to work 
dnrini;' t he winter. 

•"5. In still other eases.it may he praetieahle to lay the 
siid; oh into lands separated hy liroad, open and rather 
deep (lit(dies, into wliitdi the water Ironi the lands eould 
drain and wliei'e e\'a|)oration would he mneli more rapid 
than I rom the soil. To inei'ease the rate of exaporat ion of 
water li'oni the ditehes lines (d water loN'iuii,' trees, like tlu; 
wilh.w, could he planteil, hut tlu'se would interfere with 



309 



cr()])})iiii;'. 'Vhr better plan would he to utilize the ground 
Avith ci crop which would endure the shallow drainage. 

385. Lands Requiring Surface Drainage. — There are 
many wide stretches of very ilat land which can only be 
drained through surface channels. Such are the districts 
Avhich in recent geologic times were lake bottoms, over 
wliieh a heavy sheet of close textured clay was (hiposited. 
Soils like these have subsoils so close that were there plenty 
of fall and good op|)ortunity tO' find outlets for drains the 
rains could not k ach tlic drains freely enouah to meet the 
needs of crops. 




Kk;. l:;u. I'laii lnr ilr.-iiiiaj;^ i>l' Ininls nf llic Illinois Anl'if'lll iiriil < 'oiiiii:iiiy, 
Kdiiliiiil. llliiiiMs lAfltT .1. (). l!;il<riM 'I'lic siii;ili('St s<niiircs arc 40 
acres; (Iniihic lines shew upcii ililclies: sinulc lines are tile drains. 

Sncji fields iiiiist be plowcil in narrow lands with the 
dead fnri'ows in the direction of greatest fall in ordei- to 
provide a quick removal of the surplus rains. 

Othei- districts are so flat that the rains have not yet 
been able to cut sufficiently deep river channels to drain 
the fields en<iiigii for agi'iciiltui'iil pni'poses. The soil nilay 
be [xu-ons enongli, even a c(;ai'se sand, and yet for hick of 
natural drainage channels remain too wet to till. 
19 



r.io 

In siu'li ciiscs (1('('|) (i|)('ii (liU'li('< imisl he prdNidcd Id coii- 
vi'v tlu' water oiit. of tlic ('(nmtrv, scrviiiii,- as (Millets i'ei' 
uiidei'di-aiiis laid in the adjoininii' rields. A district (d' this 
fvpe of land drainaii'e is represented in l''iii'. I-'IO, eoNn'riuii' 
iiearlv six scpiare miles. 'Vhc donhle lines rt'prest-nr, dee)* 
o]XMi ditcdies and the sinoh* lines nnderdrains. 

Anuther draina^c^ system (d' this sort in Mason and 
'i'a/.w'ell eonnties. 111., has 17..'> miles (d' main ditch ;'>(> to 
CO feet wide at the top and S to 11 feet deep. Leading 
into these mains there are live laterals 30 feet \vide and 7 
to ',> feet deep, the wliolo system (Mnhvaciug 70 miles of 
op(Mi diteh for the purpose of pro\-iding outlets for nnder- 
drains. 



311 



CllAl'TKii XV. 
PRACTICE OF UNDEEDRAINAGE. 

Tlic I)cs1 work ill iiimIcimI r.-iiiiliia' '"in <'iil_\' Ix' done l>y \\\c 
iiiiiii. who lijis ;i t lioroii<;li ,i!,riis|) ol llic principles ol 'llic iirl, 
iin<l wlio li;is liii'l cnoiiuli pi'act i(*;i I experience to iii;il<e liini 
]»erlcctlv tiiiiii II;ir with 'llie esseiitiiil deliiils ;is tliev Viil'V 
with soil, lopoo i;i|)|i_v, clini;i'le jiiid ci"o|) conditions. 

'riiere are many case- ol' local drainage? wlicrc the area 
and expense in\'ol\('d are small, wlu're llie larnier liaviri^' 
u laii' knowledge ol llie principles (d (|raina;^c can super- 
vise or do liis o'Aii work, Itiil .vlieii lar^c areas are (o Ik; 
iiiiderdrained, where llie fall is small and the siirlacc con- 
ditions complex, it will he safest 'to entrust the htvclinf^' 
and stakiiiii' <.iit of the mains and lal<'rals read;.' loi- IIk; 
ditcher to a ciimpeteiil and ihoroiiidds' reliaMe draiiia^(! 
ciifiinecr. 

Indeed it will <;cnerally he hest an<l iiiiore economical to 
Jet, the wliide jol) if it is lar;i'e and <liliiciilt- to a man oj ex- 
pcrioncei who has est jihlished a rejiiitat ion foi' relialde work. 
Kvcn in the maltci- of di^-^iiii;' the ditch, and particularly 
in giving' it its finish, as well as in |)lacin<i- the tile, draina'^i! 
cn^'inccrs tind it <lilliciilt to find men who lia\'e the pa- 
tience, the leellnii- ol resjionsihility and the practical skill 
to do it well. A man wIk* has the ri,iilit frame of iiijiid and 
th(3 skill to do this linisliinj^- and most important woik \V(dl 
is much moi-e lo he trusted than the farmer liiiiiseH' vv'lio 
lias so imin\' duties to distract his attention and tempt him 
to rush the joh. 

Jiut while the general farmer -.hoiihl not he eneoiiraii'eJ 
to attem])t the diainin^ of lari^c ami dilliciilt ai-ea.s ou his 



312 



(iwii |)l;i('<' it is (iiiitc iiiitixirtiiiil tnr liiiii to liiivc ii clc;!!' coii- 
('('|)ti()ii of \\\r i;('ii('r;il principles of <li'iiiii:i<;(> and of what 
coiisl il ulcs I lioroiii;lily nond dclail |n'iicl ice. 




"K!. i:!l. Slinwinu' rnniis III' (lr:iiM,-inc ti 



386. Means for Determinimg Levels. — As a gxMieral rule 
I lie laviiiii' out (if a svMlcin ot diains should oidv \)v ai- 
tcuiptcd with i;'oo(l iust runiculs, two of \vlii(di arc rcpi'c- 
scutcd in l^'ii;'. i;!!. Where a i^ood drainai^c levcd cannot be 
had the: best, sul)^|^it utx' is tlu^ water le\'el, one forui of 
which is i-e|)i-esente'd iu Fig'. 131 and auotlier in Fig. 132; 
wlii(di consists cd' a piece (d' gas |)ipei ahoul ;! teet long 
nionnted on a standard and pi'o\-i(le(l with two ellvows into 
nhich ai'c cenie:ited I ,\'o pieces (d wal er gauge* glass. When 
th(^ instrument is filled with watei- the suidaees in the two 
tubes stand on a level and can he used to sight across. To 
nio\(' 't li(^ iust run lent (dose the ends (d" t he t uhes with cin'ks. 

As a. sul)Sititiite f(U- the gas pi|)e a piece (d" riihher luhiug 
may bci nsed or a piece of garden hose. 

A less i-eliablcj levcd can he iinproxised hv {irrauging an 
arm upon a standard upon which a car|»eiiter's Ie\'(d may 
be set. ()r a still more crude le\(d iiia\" lie made Irom a 



r,i3 



I'Ki. i:--. Show in^; orjc form of waler lovol. 



(•iii'|)ciili'rV s(|iiai'c iiioiiiitcd (»ii ;i liori/oiilal arm on wliieh 

a pliiiiil) hul) is suspended, 

witli w'hicli to set the 

S(]iiai-<' with its long ariii' 

level. 

387. leveling a Field. — 
In (letcniiiiiiiig I lid dilTci'- 
ences of level, in ditfere-nt 
parts of a field it is desired 
to drain, tlu; simplest 
method for the inexper- 
ienecd person is to lay out 
the field into squares of 
100 or more feet, driving 
short stakes at tin; corners. 

Set the iiisl niment at a, 
Fig. I'i.'j, midway between 
the stations I-l and 
and i-ecord I lie ; cad in; 
tluf targel placi'il iipun i he 

stake at J-1 in the tahic in llie eolinnn hea<h'd "hack-sight" 
Avhiuh is assumed for illnstralion lo he 4 I'eet. Next turn 
the instrnmeni n|>on stake 1-2, when its distance below the 
level is found lo be :',.H feet and is entere(l in the column 
headed "fore-siglit." This shows that the ground at 1-2 is 

4 ft. — 38 ft. = .2 ft. 

higliei" t hail slat ion 1- 1 . 

Ill the column headed "Klevaticni" the fiist stalion is 
given arhil rai-iiy a higlit of 10 feet al)(,\'e an assumed 
da'hiin |)laiie to a\did minus signs. I he le\(l i-< now trans- 
ferred to It and llie dislance of \-2 heloiv the inslniiiKMlt 
found to he l.l' feel which is entered in t he cnj iniiii "back- 
sight" as b(d'ore. 'riirniiig now upon I .'!, its reading is 
found to be 4 feet ami this is enlere(| in the column "fore- 
sight." 

'J^he difference in level between the l)ack sight and fore 
sight shows the difference in level between the two stations 



314 



;iii(l is placed in the ('(iliiiiiu licadcd "dilVcrciu'c." 'V\\c first 
diff('i-('iK'(^ added '(o the dahiiii, 10, oives 10.2, the hif^lit 
(if stati(iii 1-2 ah(i\-e Ihe (hilniii, phiiie. The seeoiid differ- 
VI V IV III II I 




l'"l>:. l:;o. SlidwhiK iiicIIkmI (iT li'Nclhi;; ;i lid 



ence, .2, added to the eU'vaitiou of station 1-2 f;ives 10.4, 
tho oloA'ation of station T-3 above da t inn. In this manner 
the h'\('I is nidA'ed from station to s'lation nnlii e is ii'aehed 
when it. is transferred to I" and ha(dv sia,'hts and fore sii^hts 
taken as l)(^fore, and entered in Ihe 'tahh' to connect the 
first lino of observations with the new one just be^un. 

Proeeedinii' as Ix'fore tlie hn'el is nio\('d from f to <;• and 
then thi'ouuli h, i, j, k and I '((» ni and so on nntil tlie tiehl 
is all e()ni|)leled. When |)roceedin<;' from hi^i»,her to lower 
lev<ils tlie dilfer-'nces mnst be subtracted rather tliaii added 
to obtain the elevation of the lower station. Fig. 134 shows 
the relation, of the level to tlu^ target rod along a single 
line of stations shown in profile. 



315 



Table giving data obtained in leveling field of Fig, 133. 



Statiji. 


Back-sight. 


Fore-sight. 


Difference. 


Elevation 


I-l 


4 






10 


1-2 


4,2 


3.8 


.2 


10.2 


1-3 


3.8 


4 


.2 


10.4 


1-4 


4 


3.0 


.2 


10.6 


1-5 


3.9 


38 


.2 


10.8 


1-6 


4 


3.7 


.2 


11 


II-6 


3 8 


3.98 


.02 


11.02 


II-5 


3.9 


3.995 


.195 


10.825 


II-4 


4 


4.095 


.195 


10.63 


II-3 


4.1 


4.19 


.19 


10.44 


II-2 


3.9 


4.26 


.16 


10,28 


II-l 


3.8 


3.98 


.08 


10.2 


III-l 


4 


3.6 


,'l 


10.4 


Ill-'i 


3.9 


3.96 


.04 


10.44 


III-3 


4.2 


3.775 


.125 


10.565 


III-4 


4 1 


4.045 


.155 


10.72 


III-5 


3.8 


3 93 


.17 


10.89 


III-6 


4 1 


3.625 


.185 


11.075 


IV 6 


4 


4.185 


.085 


11.16 


IV-5 




3 84 


.16 


11 



388. Contour Map of Field. — When the field has been laid 
ont as represented in Fig. 133, and the elevations of the 
several stations transferred to the map, the figures show at 




134. — Sliowiiin- iiM'lliod 



a glance wlicrc the fichl is high and wlicrc. it is low. If 
now lines are (h'awn upon the map through all })lac('S hav- 
ing the same eleivatioii the to])ogra|)hy of the field becomes 
still mioro cN'idciil to llic eye. Such lines are called con- 
tours or contour lines, and such are the dotted lines in the 
map. 

389. Location of Mains and Laterals. — It is clear from the 
contour map that the highest station in the field is VI-6 
and the lowest I-l. If then we are seeking the steepest fall 
or gradient for the main it will be found along a straight 



31G 



lino coniiectiiii:,' tlicHC two sfiitioiis. Of coin-sc no iicid will 
!)(' foiimd w'itli so ]-('<>iil;if a slojx- as this hut the |)i'iii('i j)l(' 
is Jio less 'tnu'i for ])oinf2,' so siiiiplv stale*!. 

VI V rv m II 1 




l<"jii. ];!:>.- Slli)winj4- :i syslclii <>( lilr (li-:iilis Inid oul (Hi llic leveled field of 
ViH. V.'l. (I'"niin I rrii;.-! I hni and I )raiii:i,i;e. i 

If siu'li a field is to be di-aiiied by ])laeiii,i>- bilevals 100 
feet apart about the maximum fall for tliem, and the mini- 
mum amount of tih; an<I diteliiiiii', will be secured by 
plaeirii;' the hitcrals ah.ui;' Ihc lines oi' h'Velinji', in which 
case the lines I, 11, J 11, \\\ \\ V] will constitulc ihe 
]at(M'als on oiu^ side of the main and the lin( s 1, 2, 3, -i, 5, (j 
the laterals on the other side, as represented in Fig. 135, 
Since the lines 1 and 1 are both radii of the same cii'cle and 
liave the samie elevation at llicii- outer exlreinities the fall 
or gradient will be the same or .2 of a fool per 100 feet, as 
shown on the eontour map, but along the lines V and 5 the 
gradient will be .15 feet pci" K^O feet or l.S inehes instead 
of 2.4 inehes per 100 feet along the lines I and 1. 'VUr fall 



317 



is tlicrclui'c iiitl miifonii for ;ill llic latci'als nor can it 1)0 
"wlicii tlicy arc ])lacc(l aloiii^' ])ai'allcl lines. 

If tlic licld rc(|uii'C(I (li-aiiis every 50 ffet then a iii-eater 
mean fall conld he secured and less tile wonld be rcNjuired 
if a system like that of Fig. I'JG were adopted. 




FlC. l:'i(i.— Sliiiwiii^- ;i second syslciu nl <lr;iins l;iiil (iiit on the liolil of 
Fin'. 1.'!;!. (l''i-oni I i-ri,i;:i I ion ,'inil 1 >lMin;i.uc. I 

390. Laying^ Out Drains. — W'jicn the positions of the 
mains and laterals have been decided the next stc]) is to 
mark tlie-n. with "i>rade ])ei>-s" and ''tinders.''' 'I'lie g'rade 
pegs ai'e shoi-t, dri\'en secnrcjv into IJie oi'omid jnst 'to one 
side of the intended ditch, and are placed at regular inter- 
vals apart. To one side of the grade ])r'gs ai'c placed longer 
■ones called "finders" ii|>(iii which is to be recoi'de<| the 
dejitli liclow the gra<le ])eg the dit(di is to be dng. 

391. Determining the Grade and Depth of the Ditch. — In 

doing this work the leveling b(\gins at the outlet and the 



318 



sicps nrc the siiiiic ;is those :ilrc;i(|\- (IcscrilxMl {\>y llic ticid 
level iiili', the I'esiills heiiii;- recorded in ;i 'l;iMe eiilliiii;' for 
two more coliimns when worked out than M'cre needed in 
th(> field work. 'Idiese are indicated in 'the table below: 



Tabic s/ioivi/ig Field JS'utea fur <lr(cnniiiin(/ depth of dilc/i und 
grade i\f drain. 



station 


Biick-siKlit 


K<)ro-si(,'lit. 


Difference. 


Elevations 


Grade line 


Deptli of 
(liteh. 


Outlet 


7 






7 


7 








4 





3 


10 


7 


3 


50 


3 97 


3.cS7 


.13 


10.13 


7.12 


3.01 


100 


4.2 


3 83 


.14 


10.27 


7.24 


3.03 


150 


4.1 


4.08 


.12 


10.39 


7.3B 


3,03 


2(10 


3 SI5 


3.H>) 


.11 


10.5 


7.48 


3.02 


250 


3.87 


3.82 


.13 


1(1 i;3 


7.f) 


3.03 


H(M) 


4 


3.t>9 


.18 


10 81 


7,72 


3.09 


950 


4.25 


3.83 


.17 


10 98 


7.81 


3.14 


400 


4 OS 


4 1 


.15 


11 13 


7.96 


3.17 


450 


4.0.) 


3.9fi 


.12 


11.25 


8.08 


3.17 


500 


3 97 


3 95 


.1 


11 35 


8.2 


3.15 


550 


3.75 


3 97 


— 


11.35 


8.02 


3.03 


600 





3.74 


1 


11.3(5 


».44 


2.92 



III 1^'ii;'. !.")T, whicli is a |»roliie of the data in the tabl(i 
showiiii;- the outlet of the drain at A, the tirst. stake at () 
and the second al .M), etc., up to (iOO, both the lines (d' 
i;i'a(lean(l tliC'daluin plane arc shown. ()ii each niiinbered 
stake is <;i\-en the de|)tli of the ditch below the lop of the 
i^rade pci;', and below the peii' has been set the lii<;lit of tlu^ 
botfoin (d the ditch aboxc the datiiin plane. 

Since the oiiilet in this case is 7 feet abo\'e dattini and 
the surface at COO feet is 1 I.IU; feet the total fall is 

11.30 feet — 7 feet 4.30. 

lint if it he depth (d' tlic ditidi at tlici up|»er cud is made 
2.!)2 feet the available fall will IIh^u be 

4.30 feet — 2 92 feet== 1.44. 
SiIlc(^ the dit(di is 12 times 50 feet loui;- the fall will bo 

J 44 

-y^ -- .12 feet i)(>r fiO feet. 

or .24 feet per 100 feet. At eacdi 50 foot station tlien the 
bottom of tlu^ ditcdi abovo datum plane will be found by 



310 



acldiiii;- .12 fool, lo 7 I'cct, wliidi is the Iiciiilit of t lie oiitlot, 
for tliJli of the .-ccoikI sliilinii; llicii . 1 1! feet iiddf d In this 
jiiiN'cs tlic tliii'd station and so on, 'thus: 

7, 7.1i', 7.24, 7:M, 7.4S, T.CU), 7.72, 7.S4, 7.U(\, 8.08, 
8.20, S.;52, 8.44. 

200 250 ^^ 



50 100 "0 



350 *^ 150 500 650 «00 




£^--'="^'-^ 2-s^^-^--.;^ VS^ y^ ' V'-'OAtOmCplane"/ t; ^^'■'^'-Ssz^-^"-^ ^'s iriJ-^ ' 



Fn;. 137.— rnililc (if diicli sliik.'il rcidy fur ili^rKiii;,', witli dcpllis for the 
(lilcli ;il llic scvci-.-il sliilioiis. 

If these (Miinihcrs arc suhtractcd froMi the hiiihts oi tlie 
surface of the ground ai tho respective ])hices tlie differ- 
ence will he the de])th flu* ditch nnist he du£>' at those 
places, and the figures which are placed upon the finders 
for the instniclion of the men in diiiiiinii'. These fi<2,'ures 
are given in tlie tahh' in the colnnin "(h pth of dit(di." 

The ex])erienced (h-ainage engineer with acciwate tele- 
scojx* level makes the details of lev(ding, es'tahlishing the 
grade and mai-kinii' the gr^wle pegs simph'i- than here given 
hut it is not safe for a farmer with a (dieap h v(d to follow 
liis methods. 

392. Changing from One Grade to Another. — It may liap- 

]ten in hiving on! the ditch that it is impracticable to fol- 
low a single grade on acconnt of ha\'ing to dig too deep in 
some ])lacers or of leaving the lih' too close to tlu^ surface 
in others. Suppose in the last profile (391) the ditch was to 
he ;")()() fet^t loiii-cr and that in this 500 feet there had been 



»20 




321 



it rise (if lull <i iiiclics. Il Is r-lciir lluil lo hold ;i siii;ilc ^rado, 
milking I lie ii|i|)( r (lid ai' Ak diidi ji.Itii IVci deep, would 
l'('(|iiiic ;i ^Kilter dcplli in ollici |ioilioi!s llijiti iii'<'css;ii'y. 
Ilill if the iii;idc is cliniij.'f'd ;it (lie (iOO Inoi slii'lioti so aS 
lo ^i\ (• il fill I (d 

■ ■', .1 11. per 100 It. 

il sidliciciit dc|»tli will lie -iciircd iiiid liibor in <li<i'^in^ 
sa\'c(|. 




!<:. I.',;). Sliowliij,' llii- ilJU-hiiii; line ;iti<l the •'oriinji'ijii'iiji'iil r,C iWn^ilun. 

393. Ditching Tools. In diooi,,o. ., ,|i,,.|, j, j^ ., ,,,uiU;r of 
irst inipoi tiiiicc to li;i\c siiitiiMc tool-^: imd w liiiicx'cr olse i8 



322 

(•lioscii llic iiicii sliiHild lie [ir-dv idcd willi lii'sl chiss s|»;hI('S, 
k('|ii|. mIi;ii |i ;iii(l inr li'diii iiist. 'I'lic spiidc wliicdi ^i\cs llio 
l»('sl s;il ishiclioli li;is ;i liili<j,', lliili, iiiiiidw ;iiid (•iir\rd l)l;idc. 
'I'lic cm \ ;il iiic is of lirsl iiii|i«ii'l;iiicr in ^i\iiii;- j^rculcr st i IV 
licss iilid id lowing' t lie M.'idc In lie iiindc I liiiiiicr ;iiid lii^lilrr. 
Tlic s|)iid(' slididd lie ii;iir()\\ ;iimI ihiii In ciKdilc llic user In 
i<ii'«*<' il liill Iciii'jii iiilo ihc sdil w'illi ihc pressure (d' the 
l<i<.l :iiiil so MS I.I lie ;dili' hi le;i\'e llie liiillniii nl ilie dilcli 
li;iri(iw, reiii(i\ilii;' ;is lillle e;irtli ;is pdssilih . 

Ill Kiij,'. l-'ll ;ire show II |\\(i loriiis of s|i;iih's, I'oiir lih- 
hoes, which ;ire used in linishini; I he holloin of the dilck 
iiiid i'cino\ inii ihc hiose e;iflh, ;ind ;i lih' hook, used in |ihi(!- 
iii^- Ihc I ih'. The series of h;iir loiics shows \\n-t^r di lie rent; 
l.onis in use. 

394. Making' the Ditch Narrow and Straight. To nnikc 
lh(^ dihdi -||;iiulii ;| slroiiii' jiohl line is sti'iiUdicd linil iic;ir 
tll(i Wlirr.'ice ;iiid I iiicdics li;ick rimn llicedi;('. il'lhcdiudi 
is ifo lie Old V :'..'i jo;; led (|ee|) il need lie no w idcr ;il I he 
l<'|i llniii one fool, as shown liy I he leiii;lli of lilc in l''ii>', 
l."Il>. \\ \\c\-{' llic ditch lillisl lie l.."> to Ti feel :iiid icceivc a 
(i inch lilc, as shown in l<'ii;-. I I I, il iniisl have a wiihli al- 
I he lo|i of I .'i |o IS inches. 

'Idle dilcher i^ trained lo cut the walls slraii^hl vvilli an 
('\'cii slope lo. llin lioilldin so as to^ lea\'e a slrai^'lil liin^ 
aloiiii' Ihc hotloin lo reccixc I he I ih'. In I'^ij;'. NO it will he 
seen llial loiir iiieii arc workinj^' in line to coinplclc. Ilii; 
dcplh of the (lit(di w lii.di is !.:• feel at llic place. 

395. Shaping- the Bottom and Bringing- It to Grade. In 

I^'i.i;'. I I I the man in llic forc^TouiK] is iisin^' th(^ tile hoc to 
(dean out llic last loose earlli and lo hrinii' ihc holluin to 
}i,'r'ad(^ and proper shape to rccci\'c ihc tile. The uradc is 
sccnrcd hv stretching;' Ihc dihdicr's line tiii'lit, and on (ho 
slant the holtoin ol' llio dilcli is to ho i^'ivon, and ;it a known 
liii^hl. aliovc it. It is then oiilv neccssarv for I Ik c\pcr- 
iciK'cd mail to nsc a mo.'isnriiii;- rod to secure the depth and 
;;rade desired. 



'.\<-)'\ 




r>24 



W'lifii llic i'('(|iiisilc skill :iii(l jii(ii;iii('iit li;i\(' luil been 
:ic(|iiiic(l l(ir lliis work llic 111:111 is proNidcd willi ;i. iiicas- 
iiriiif;' stick willi ;i slidiiiii;- iinm wliicli c.xIcikIs jiI, iMi;-lil, 
iUl|j,"l('S to tile itid :iiid loiii;' ("ii(iili;li li> rciudi the li'mdc line. 
It. is llicii (iidv iicccssnrv to liold llic Vi^A n\- "ditclicr's 
s(|ii:ii'c" |iJiiiiil) Id kiKiW" wlicl lici' llic ditch li;is the (l('|»th 
desired. 



396. Placing- the Tile. When llic dilcli lias boon fiiiislied 
Ihe lih' ;ire laid with the tile hook, ns vc])i'<'S(nit('(l in Fi^. 
I I'J. With the aid n\' ijiis t()(d lliev are placed ra])idly 
and acciiralclv withdiil <j,('l I Iiiii,- into the dit(di. (Ircatcai'O 
shdiild alwavs he laki'ii to liirii and sliil'l the tile until a 
perlecllv (dose |iiiii| is made all around. It docs not, do to 
siiii|dv have llicni iiie( I cii the ii|i|>er e(|o(.^ thev slio\dd lit 
s(|iiartdv and (di.scdv lhr(Mii;ii the ciilire circiini Ici'cncc and 
it nccessarv tile tee inucdi \\ai|tc(| jo |ieriiiil ol lliis must 
he discarded. 

Sdiiie |n(dcr to place the tile with llic hand, standing;,' in 
the ditch npon lla 111, cii\-eriiii;' llieiii as rapidl_\' as laid with 
■I to (') inelics (d' earlli, lakiiii^' care Id' ^cl il I lidrdni;iil_\' 
pa(d<ed and net tti i;el the tile dut id' alia,nnicnl. 

The urealcsl care slionld he exercised Id pacdx the earth 
I lidrdnii,lil V alidiil the jniiils so as to avoid lai^c d|)eii 
cavities I hrdii^li \\hi(di the water niav rush diirini;' iieavy 
rains, u ashing dirt inid I he I i le. 

Tile la viiiu' slididd lie-in al llii' <intl(l (d' llic iiiaiii, pre- 
cccdiiiii' upward lo the lirsl lateral, where i1h> jnnclidii 
should he made and lile ciKaiuii laid in I he latci'al to pcr- 
niil the iiiain Id he parllv lilled. The main inav then he, 
carried on iinlil the next lateral is reached, when tllis 
should he coiiimciieed as hiderc. ('are should he cx( rcisi d 
not, to lca\'e the upper end (d an untinished lim* of lile opiMi 
tor lica\' V rains to wash mud into it . 1 I' I he line cannot 1)0 
linished lud'ore the rain the end iiiav he iiuai'tled hv t losinii; 
it with a heard, hri(d< er hiiiudi (d t^rass. 




'Jt 



320 




n^: 



>« 






028 

397. Filling the Ditch.— After the tile have been placed 
and covered with the first hiyer of earth the balance may 
be put in bv any convenient niethod. A common and ex- 
peditions way is re]n'esented in Fii>-. 143 where a plow is 
drawn by a team at'tachcd to a Inuix evener. For tlu^ finish- 
ing the ordinary road grader makes an efficient tdol. 

Still another ii eth()(l is to iisi- a light board scra))er pro- 
vided Avith handles to l)e held against the bank of earth, 
which is drawn into the (Hteh by a team on the opposite 
side drawing from a ro])^ and l»ackiiig when the scraper is 
emptied. 



329 



EURAL ARCHITECTLEE. 



C'lIAPTER XVI. 
STRENGTH OF MATERIALS. 

A knowledge of tlic ])iiiK'i])les ooveriiing the strength of 
materials is helpful jilong uuiny line,'^ of farm practice and 
particularly in the construction of farm buildings. 

398. A Stress. — When a })ost is jilaced upon a foundation 
and a load of two thousand pounds set u]>on it the post is 
nndergoing or oi)j)osing a stress of two thousand pounds. 
AVheii a rope is supporting a load of one thousand pounds 
in a condition of rnst it is subjeoii to a .sfr(s:< of one thou- 
sand i>(;unds. The ioists under a mow of liav are subjected 
to a .str< .ss measnied by the tons of hay which they carry. 

399. Kinds of Stress.— Solid bodies may be subjected to 
three kinds of stress which tend to break them and will 
do so if the strevss is great enough. I'hcse are: 

1. A crushing stress, where the load tends to crowd the 
molecides closer together, as ndien kernels of corn are 
crushed between the teeth of an animal. 

2. A stretching stress, as wdiere a coi'd is broken by a 
load hung upon it. 

■K A twisting stress, as where a screu' is l)roken by 
trving to foi-cc i! into h;ir(l wo-id with a screw-driver. 

400. Strength of Moderately Seasoned White and Yellow 
Pine Pillars. — Ah', ('has. Shaler Smith has (h^duced, from 
experiments c(jnducted by himself, the following nde for 



:];50 



etreiigiih of iiKHii'iatcly .-ca-oued wliito and vcllow pine 
pillars : 

Eule. — J)ir/i/<' III,' siiiifirc of (he length in inches In/ the 
square of the least thickness in indies; multipty t lie quo- 
tient 1)1/ .004 and to fhis product add 1; then divide 5,000 
hy this sum and llie rcsull is llie strenqth in pounds per 
square iiirli <>f aira nf llir cud of llie post. Multiply this 
result hy the <irea n/' Ihe cud of llic post in inches, and the 
answer is the slrcuqlh of Ihe post in pounds. 

In applying- this lulc in the c(.nstrnc"t.ion of farm bnild- 
ings the timbers shonld not he trnsted with more than one- 
foin-th to one-sixth of the theoretical load they are com- 
piitod to carry, hecansc the tluHn-etical results are based 
upon averages, and there is a wide variation in the streng-ifh 
of individual pieces. 

Table of breaking load in ton H, of rectangular pillars of half 
seasoned white or yellow pine firmh/ fired and, equally 
loaded, computed from C. S. Smith's formula. 



■3-^ 
H 


Dimensions of rectangular pine pillars in inches. 


►3.S 


4x4 


4x6 


4x8 


, 1" 
4x 

tons 
30.2 
21.7 
16.1 
12.4 
9 8 


4x12 

tons 
36.3 
26.1 
19.4 
14.9 
11.7 


6x6 

tons 

44.. 'i 
34.6 

'J.l.'c 

21.7 
17.7 
14.6 
12.-<i 
10.3 
8.8 


6x8 

tons 
fi9.:^ 

:^6.:i 
29 
23 ft 
19.4 
16.2 
13.7 
11.7 


6x10 

tons 
74.1 
57.7 
45.4 
36.2 
29.4 
24.3 
20.3 
17.2 
14.7 


6x12 

tons 
88.9 
69.2 
54.4 
43.5 
35.3 


8x8 

tons 
10). 7 

81.2 
69.7 
57.9 

48.4 
An a 


8x10 


8x12 


10x10 


10x12 


8 

10 

12 

14 

16 

18 


tons 
12.1 
8.7 
6.5 
5.0 
3.9 


tons 
18.1 
13.0 
9.7 
7.4 
5.9 


tons 
24. i 
17.4 
12.9 
9.9 
7.8 


tons 
1-6.9 
105.3 
87.1 
72.3 
60.6 
51.0 
43.4 
37.4 
32.3 


tons 
1,52.3 
126.3 
104.5 
86.8 
72.7 
61.2 
52.1 
44.8 
38.8 


tons 
182.7 
158.6 
136 7 
117.4 
101.0 
87.2 
75.7 
65.8 
57.9 


tons 
219.2 
190.3 
164.0 
140.9 
121.2 
102.6 
90.8 
79 


20 












24.3 34.8 
•!0.6 29.9 
17 i; 9?; Q 


22 












24 












69.^ 



















In the application of the rule for the cnishing load for 
posts in barn building the length referred to is the greatest 
distance between any supports which prevent the post from 
bending. 

401. Bearings for Posts. — In order that a post may carry 
its maximum load it is important that it rests squarely 
upon its support and that the load carried presses squarely 
upon the post. If the ends of the post are not square or if 



:):'A 



the l»(';ii-iii<i' is ouf of rnic so rliat rlic strain comes upon one 
edge the eairviui;' powc i- is nieativ hsst iieil. 

402. Tensile or Stretching- Strength of Timber. — The ten- 
sile strength of imiterials is measured by the least weight 
which will hi'eak a vertical rod one inch s(]iiare firmly and 
squarely fixed at its upper end the load hanging from the 
lower end. Below are given tlie results ot experiments 
with different varieties of wood, hut the strengths vary 
greatly with the age of the trees, with the part of the tree 
from whicli the piece comes, the (h'gree of seasoning, etc. 

Elm r, )00 lbs. per .s(iuare iach. 

American hickory ll,00i)lbs per sciuaro inch. 

Mapla 10,000 lbs. per siiiiare incli. 

Oak, white ai.d red 1U,0L'0 lbs. per square incli. 

Poplar 7,OJ0 lbs. per 5(1 larrf iLcli. 

White pine 10,000 lbs. per S(iuare inch. 

403. Tensile or Cohesive Strength of Other Materials. — 

American cast iron 16,()U()to iiS, 000 lbs. per sq. inch. 

WrouKht iron wire, annealed 30,00f)to 00,00 ) lbs. per sq. inch. 

Wrought iron wire, hard fiO.OOli to 100,000 lbs. per sq. inch. 

Wrought iron wire ropes, per sq. in. of rope 3S,000 lb-, per sq. inch. 

Leather belts, 1,50 J to 5,0JO, good ;i, 000 lbs. per sq. inch. 

Rope, manila, best 12,(00 lbs. per sq. inch. 

Rope, hemp, be-t 15,000 lbs. per sq. inch. 

404. Transverse Strength of Materials. — When a board is 
placed upon edge and fixed at one tnd as r(.'])re.sented at A, 
Fig. ]44, a load acting at W puts the upper edge under a 
stretching stress. 




We know from experience that in case the board breaks 
under its load when s(j situated the fracture will occur 



332 

!-<tiii('\vlicif lU'iir .")-(;. Xdw ill i, Viler tlia' This iiiav t:ik(; 
])1{U'C there iinust he, with white jiiue, accordini.' to (402) a 
tensile stress at tlie upper cdiic of ten thdiisand pounds to 
th(^ scjuaie inch, and if the hoard is one iiudi I hi(d< t \\v upper 
ineli shonhl resist a stic-s of 10, 000 pounds at any point 
from f) to 1 ; hut we knew that no sncdi load will he earried 
at W. The r( ason for this, and also for its breaking' at 5 
rather tha'i at any other poiiit. is found in the fat t that the 
load acts upon :i le\-er arm .nIiosc Icnulli is the distance 
from the point of attaehnit 'ut of the load to the hreaking 
]H)int, w'lurever that may he, and this being true the great- 
est stress eonies necessarily at ">. 

If the boaid in ipiestion is 4M iiudies long and *I inclics 
wide, it will, in breaking, tend to re\dl\c about ,lic center 
(d the line, .")-'», and the upper lliree iiudies will be put 
under the longitudinal strain, bnt according to (402), is 
capable of withstanding 

3 K 10,000 lbs. = :50,000 lbs. 

without l)i-eaking; bnt in carrying I he h ad at the end as 
shown, this cohesi\'e pi wer is acting at the sIku'I end of a 
hciit lever whose mean lenglh of power arm is one-half of 
4-5 or 1.5 iuidies, while the weight arm is forty-eight 
iiiolios in length. It should therefore only be able to Indd 
at W lt;)7.5 jionnds, for 

as P P A = W K W A, 

we have 30, 000 X 1-5 = W v 48. 

whence W = 1^1^ = 937.5 jbs. 

A\'hen a l)oard, in cNci'y respect like the one in A, Fig. 
144, is placed under the conditions re])resented in either B 
or (\ Fig. 144, it shonhl recpiire just four times the h^ad to 
})reak it, because the board is ])ractically converted into two 
levers Avhose jiower-arms renniin the same, but wliose 
w( ight-arms are only one-half as long each. 

405. The Transverse Strength of Timbers Proportional to 
the Squares of their Vertical Thicknesses. — ( 'ommon ex])eri- 
ence demonstrates that a icu'st restini!' on ediic is able to 



ciiri'v ;i imicli iiTcnt*'!' load tliaii wlicii l\iii_<i' tlat-wisc. If wo 
[(lace a 2x4 and a i^x.S, wliicli dilfcr oulv in thickness, on 
edge their relative !stren_i;t]is are to eacli other as the squares 
of 4 and 8, or as Id to (i4. 'I'hat is the 2x8, containing- only 
twice the amount of hnnher as tlu 2x4 will, under the con- 
ditions named, sustain foui- times the load. The reason for 
tliis is as follows : In Fig. 145 let A represent a 2x4 and B 
a 2xS. in each of these cases the load draAvs lengthwise 
upon the u|)per half of the joist, acting through a weight- 




© 



i 


p 


2 x8~ 


W 


1 


lOlN 


^^ 


^ 




A 



Fid. 145. 







arm F, W, ten inches in length, to overcome the force of co- 
hesion at the fixed ends, whose strength, according to (402) 
is ten thousand pounds ])er s(piare iiudi, or a total of 

2X2 X 10,000 lbs. = 40,000 lbs. in the 2 / 4 joist, 
and of 2 X 4 X 10, 000 lbs. = 80, 000 lbs. in the 2 / 8 joist. 

These two total strength>s hecome ])owers acting through 
theii" res))ective power-arms V, P, whose mean lengths are, 
in the 2x4 joist, one in(di, and in the 2x8 joist, two inches. 

.\ow we ]ia\'e 

PXP A = WX W A, 

and sul).<tituriiig the nuinci'ical values, in tiie 2x4 joist, 
we iiet 



4X10,000 1 =r Wx 10 
or4y 10,000 = low, 
and W = 4,000. 



334 

Siiiiil;irlv, l>v siiltsi i'l 111 iii<^' iiiiiii('ii(-:il \;ilii(s in I lie ciiHO 
III" I lid L'.\.S j((isl we i^c\. 

H l(»,()(l() ti VV 10, 
or It; 10, 0(10 10 W, 
iiiiil W 10, 000. 

I I. I liiis ;i|i|)r;irs I li;il I lie londs I lie I wo ji li-'l s will cjiitn' iirci 
lo ciicli oilier ;is l,(»(l() is lo M;,(HM), or iih 1 is lo I; l>iil, 
S(|ii;iriiii;' llic \ciiic;il lliickin'ss of llic I, wo joisis in (picH- 
I ion we i;c|, for I lie ■J,\ I joisi 

I I 10, 

,'1111 1 fur llir '1 ,- H joisI, 

H H <;i; 

l)nl. \i\ is to (II IIS I is lo I, which shows Ihiil. t.h(^ iriuisvcrsc! 
sl.i'cni^l lis of siini I.I r I i in Iters jire proporl ioiiiil lo I he S(|lliU'C8 

ol I Ik 'I r \ crl iciil d iiiinelei's. 

406. The Traiisvcr.se Strenjith of Materials Diminishes Di- 
rectly as the Leiij^'tli Increases. Ii \ ilMie rejidilv seen froin 

;in illS|iee| i<Hl of Kin,'. I l."», lli:il lelii;l lieiiini;' lln' pieces of 
joisIs, wliil(> I lie oilier (lillieiisions reiii;iin 'llie s;iiiic, 
lenuilielis llie loiii;' ;irili of llie lever, while llie sliorl ;iriii re 
Jii.'iiiis niicli!iiii;('(l ; iind since llie lorce (d' cohesion reiii;iiiis 
ninillel'ed, llie |o;(d iiecess;ir\- |o (.\ercoiiie || iiiiisi he less ill 
proptu'lioii ;is llie lever iii'iii upon which il ;icls is incrciised. 
'IMiiis, if llie l'\S in l^'ii;. I 1.') is nuide 20 iiiclies lon^', wo 
sJiiill li;i\'e, 

I* l'.\ W W.\ 

Mild hv siihsl il III iiii;' llie iiniiieric.il \;iliies we n'cl, 

HO, 000 "J W '20 
W H,0()0 

iiislriid of Mi, 000, ;is found in (405). 



407. The Constants of the Transverse Brcakinf^- Streiifith of 
Wood. Since llir l;i\vs >/i\i-\\ ill 404, 405, imd 406 ;i|.))ly l,o 
iill kinds ol niiilcriiils, il rullows lli:il, llic ;i<'1iinl l)rc;ikiii^ 
•strcn^lli (il <lirrcrciil liind of in;ilcn;il- will <lc|M'n<l n|M.n 
llin ckIk -i\c |)().\cr of llic niolci-iili'-; ;i- well ;i~ Mjion llic 
I'iriii .'iimI ilinicnsions of llic ImkIv wliicli llic\' cdii.liliitc. 
'I lie l»rc;il<il|c' slrcii/^lii df ;i Iic;iiii ol' ;iiiy iii;i I cii;i | i- ;i|\vil_y,S 
in |»r()|)(,rl ion {<> ils |»rc;i(|||i, nriill i |)l ic<l l)\ llic -(|ii;irc of \\a 
<lc|il II, (li\ i(|<<l liy ils Icn^'l II, or 

IJn-adlli the Hi|ii;irc of I lie (|(|)( |i 

;iimI iI llic l)rc;|(|||| ol ;i piece of wlillc |iinc III inclic^ is I, 
ils i|c|(||i ill indict M), ;iiii| il-, l<'ii,"lli in led |(), -.vc sliiill 
liiivc, hiking I lie Icn;^! Ii in Icct, 



10 



.\o\v il" we linij l»v ;iclii;il lri;il, \>y j^r;i(ln;illy ;i(i<lin;^ 
weiji'lils to 'llic cciilcr ol -iicli ;i Itciini, tli;il il lirciik-. Ji.t, 
Is, 000 jMiiinds, iiiclinl iiii.' IkiII ils ovn wci^jlil, llic imMo he 
t ween I liis ;i!|(| fori \- will lie 






;iii<l ;i- llii-, I'jilio i,^ jilwjiys loiiiiil loi' while pine, aIich the 
lii<;i(|ll] :iiiil <lc|)||i ;irc liil:cii in iiiche-, ;iii(| ihc leii^lli la 
Icet, no nnillcr "Ii;il llic i|mii-n loii- of llic linihci's iiniv Ite, 
450 Ih (mIIciI i'l-^ l»rc;ikinc- coii-|;inl for ;i crMilcr lo;i<l. 

V<tv olher niiilcriiils this (•(.nsliiiil is (Jinerent, :iiii| Inis 
l>c( n ilcteiiiiiiic(| hy ex|K'riiiietil, iin<l ^ivfii in tiihles in 
\iirioiis wc/rks rehit iii^- to siieji ^iiiijecls. 'I'ln' roljowin;!' ;ir<r 
'Ijikeii IVoMi 'I'riiiltwiiie. 



336 

408. Breaking Constants of Transverse Strength of Differ- 
ent Materials. — 

Woods. 

American White Ash 650 lbs. 

Black Ash 600 lbs. 

American Yellow Birch 850 lbs. 

American Hickory and Bitter-nut 800 lbs. 

Larch and Tamarack 400 lbs. 

Soft Maple . , 750 lbs . 

American White Pine 450 lbs. 

American iellow Pine 500 lbs. 

Poplar 5,50 lbs. 

American White Oak 600 lbs. 

American Red Oak 810? lbs . 

Metals. 

Castiron 1,500 to 2,700 lbs. 

Wrought iron, bends at 1,900 to 2,600 lbs. 

Brass SSOlbs. 

409. To Find the Quiescent Center Breaking Load of Mater- 
ials having Rectangular Cross-sections, when Placed Hori- 
zontally and Supporteu at Both Ends. — In placing joists and 
l)eams in barns it is important to know the breaking load of 
the timbers used. This may be Jetermincd with the aid of 
the following rule and the tal)le of constants given in 
(408) : 

Rule. — Mulliphi ihe s<ni(ii-c of the dcpili in inches by 
the breadth in incites and this In/ flie tireal'iiKi constant 
(jiv^-n in (408); divide tJie i-csalt /;_// Ihe cleai- iciKjth in 
feet and the result is the load in pounds. 

But in the case of long heayv timbers and ii'on beams 
onedialf of the clear weight of the beam must be d('(hicted 
because tliev mnst alwavs carrv their own weight. 



Breaking load 



Square of 1 
depth [■ > breadth in inches - Constant 
in inches ) 

Length in feet. 



What is the center breaking load of a white pine 2x1^ 
joists 12 feet long^ 



Dill 12X12X2X450 ir>onniK 
Breaking load = — -(^-^ = 10, 800 lbs. 



What is tlic l)icakiiii:' lna<l foi' the same 10 feet Imi^'^ 14- 
fcct loiiii^ I'i tV"t luiio- :; is feet loiiu' ^ Solve the same prub- 
Ic'ins f(ir other woods. 

410. General Statements regarding the Quiescent Breaking 
loads of Unifortn Horizontal Beams. — If the center ([uieseent 
hreakinii' load be taken as 1, then, when all diinen'^ions are 
the same, to find the breaking load: 

(1) When the l)eani is fixed at both ends and evenl}^ 
loaded tludniihont its whole length, mnltiply the result 
lonnd b,v (409) bv two. 

( 2 ) When tixed at onlv one end and loadetl at the other, 
divide the result obtained by (409) by four. 

(3) AVlien fixed only at one end and the load evenly 
distril)uted divide the result obtained by (409) bv two. 

( 4) To timl the breaking load of a eylindrieal beam, tirst 
iind the breaking load of a siiuare beam having a thickness 
ecpial to the diameter of the log and nndtiply the result by 
the decimal .581). 



411. Breaking Load of 
Rafters. — In finding the 
hreaking load of tinihers 
placed in an oblique posi- 
tion, as shown in Fig. 
146, take the length of the 
rafter equal to the hori- 
zontal span A, C, and pro- 
ceed as in (409) and (410) 




412. Table of Safe Quiescent Center Loads for Horizontal 
Beams of White Pine Supported at Both Ends. — In this table 
'the safe load is taken at one-sixth of the theoretical bre;ak- 
ing load. This large reduction is nuide necessary on account 
ot the cross-grain (d" tind)ers and joists and the large knots 



OOQ 

ooo 



M"lii('li weaken \'ei'v iiiateiiallv the ])ieees. AVliere a judi- 
cious seilectioii is uiade in ])laeiiii>- tlu- jois-its, laying the in- 
liereutly weak nieces in 2)lac(»s wiiere little strain can come 
upon tlieni, juuch saving of Inniher may be made. 



a 


Span 10 feet. 


Span 12 feet. 


Span 14 feet. 


Span 16 feet. 




Breadth. 


Breadth . 


Breadth. 


Breadth. 


fl-9 


2 in. 4 in. 


6 in. 


2 in. 


4 in. 


6 in. 


2 in. 


4 in. 


6 in. 


2 in. 


4 in. 
lbs. 


6 in. 




lbs. 


lbs. 


lbs. 


lbs. 


lbs. 


lbs. 


lbs. 


lbs. 


lbs. 


lbs. 


lbs. 


4.... 


210 


4>>0 


720 


200 


400 


600 


IV 


344 


516 


1.50 


300 


450 


6.... 


510 


l.O'-O 


1,620 


450 


800 


1,350! 


386 


772 


1.158 


336 


672 


1,008 


8.... 


9(50 


1,920 


2,8S0 


8(J0 


1,600 


2,400 


686 


1,372 


2,0.58 


600 


1,200 


1,800 


10.... 


1,500 


3,000 


4,500 


1,250 


2,,')0i) 


3, 750 


1,072 


2,144 


3,216 


936 


1,872 


2,808 


12.... 


2, 160 


1, 320 


6,480 


1,800 


3,600 


5,400 


1,544 


3,088 


4,63: 


1,350 


2, 700 


4,050 




Breadth. 


Breadth. 


Breadth . 


Breadth. 




4 in. 


10 in. 


12 in . 
lbs. 


8 in. 


10 in. 
lbs. 


12 in . 
Ib"^ 


Siu. 


10 in. 


12 in. 

lb.s. 


Sin. 


10 in. 


12 in. 




lbs. 


lbs. 


lb..-. 


lbs. 


lbs. 


lbs. 


lbs. 


lbs. 


4.... 


960 


1,200 


1,440 


800 


1,000 


1,200 


688 


660 


1,032 


600 


750 


900 


6.... 


2, 160 


2,701) 


3,240 


1,800 


2,2.50 


2,700 


1,5U 


1,930 


2,316 


1,314 


1,680 


2,016 


8.... 


S,S40 


4, SOD 


5, 760 


3, 200 


4,000 


4, too 


2, 744 


3,430 


4,116 


2,40U 


3,000 


3, 600 


10.... 


6, 000 


7,500 


9,000 


5,000 


6,250 


7,500 


4,28^ 


5, 360 


6,432 


3,744 


4,680 


5,616 


1<5.... 


8,640 


10,800 


12,960 


7,200 


9,000 


10,800 


6, 176 


7,720 


9,264 


5,400 


6,750 


8,100 



413. Selection of Lumber to Increase Carrying Capacity. — 

It is ])().-<sil»le to greatly increase the cari'ying ca])acity oc a 
lot of joists or of a set of Ix aiiis l>y giving attention to the 
luinher u^vi], selecting tlie e\i(lently strongest pieces for use 
where it is known tlie heaviest strains will come. Some- 
times a joist sh(»ul(l he reversed or turned the other side up 
in oi'(hM' to eiiahh' the j»iece to render its highest service. 
In the arrangement of joists under a hay bay or granaiy, 
where hea^■y loads are to be carried, the cross-grained pieces 
and those Avith exce})tionally large knots shouhl l)e well dis- 
tributed among thei stronger ones, making the evidently 
weak come Ik twecn those evidently al)o\'i' the aveiage in 
s4renuth. 



414. Braces. — There are two princi])les iniderlying the 
use of hraces to give greater strength to lumber, 1. That of 
equalizing the load, making it fall more heavily upon the 



339 

S'tro'iiger iiiciiiIk'I's. -2. 'I'hnt of sli(irl(iiiii^- t lie tree span. 

The first l-i\sli is illusti;it('(l in tlic- rows of bridging used 
between tlie joists in a floor. In these eases Avheii a weak 
inembi'r is hridi^cd between t >.vo stronger ones a pcrtion of 
its h)ad, beeanise it viebis soonest, is tbrown by tbe bridging 
upon file stronger, and stiff'tr lloois are tbus secured and 
the breaking of intUvichial })ieees ))revente(l. 

Jhaees in nearly ;dl eases are, in prinei])le, either posts 
ov else tliey are si'spcnsion rods wliicb allo.v tbe strength of 
'thei nniterial to be utilized unafl'ected by tbe ]»rinei})le of 
leverage, tbe strei-s Ix'ing a direct ])nll or a ])nsb, bimging 
into ])lay tbe fnll tensile or cinsbing strengib of the nia- 
teiial. 

To sboi'ten ibe fi'ce span of an iS-fViot joist or timber 
two feet at eatdi end by means of suital)le braces is in- 
creasing its cari'ving |)(iwer '2X.~> ])vv cent. 

it is nincb more inipoitant to pay strict attention tO' these 
nnitters of strength at the })resen'r time than in former years 
both becanse bunber is higher and often (d' mncli inferior 
([nality. 

415. Constructing Timbers from Two-inch Lumber. — It is 

often not oidy .'lieaper bnt better to construct SxfO or 8x12 
heanis by pntting togetbcr I'xlO oi' l^\12 ]dank, the timber 
1 bus const 1 nctedcften being stroiigci- tban a solid ine would 
be beicause weak places are; more likely -to be distributed so 
as to give a greater nu>an strength, it is of coui'se not true 
that a fOxlO so madc! would b(^ stronger than a solid timher 
(d the same dimensions if jxitli were (d' hiubest erade 



416. Form of Barn Frame. — During ])ione(r days, when 
saw mills were none or few, it was mucli easier to secure the 
needed stabili'ty for a barn by hewing a few heavy timbers 
of suitable length and putting them together with I)races 
than it was to use the 2 inch bunber now so comnmn in the 
frames of dwelling houses. 

Since tbe old type ui' bai-n fi'anie was de|)ended upon to 



340 



liivc the ii('('(l('(l ^tahility, little ov im sii]>|)(irt (-(.ii/inif tVoin 
the sidiiiii' in- shcctinii', it \v;is iicccssnrv to use lai'iic timbers 



^^'^V^C^,.^^ 





Vu:. 1-17 



and to fVaiiic llieiiL toiicther and hracc tlicui vcvy securely 
iiiakiiiu' a stnictme eostlv both in material and labor. 



417. Plank Frame. — The hii;li j)riee of hnnber has led to 
an etioi't to imitate the coiistriietion of the old lie'vii timber 
frame barn in the eoiistniction of essentially the same type 
of frame but iisino' plank spiked together instead of' tim- 
bers. This type of frame is represented in Fig'. l-iT. 

The frame so made is strong and not as ex])i:'nsive as ono 
of heavy timbers at the ])resent ])riees but it is neither as 
sim])l(^ in eonstnu'tion nor as (dieap as a frame for most 
barns can be made. Now that the eonditi()ns .\iii:'li made 
the heavy timber frame a neet'ssity ha\'e disaj)]>eart'd there 
is no need of imitating it by splicing Inmber. 

418. Balloon or House Frame. — The reason for not ad- 
hering to the ^)ld ty|)e (d' barn frame is beeanse ir j)ermits 
of no advantau'e beini>- taken of the inherent strenuth oi the 



341 



\\ I'fii the .r\v.. incli Imiil,,.,- used in il,,. m|.,„1- f 

;""-'«■ >". i-.» ..».i" ,,:';,;,":; 

J''';;';<'^l<-Ha.lsa>HlK>sJal.orarom,„ire(l '"^'"^'^■^^ 

\\ liciv I he l)iiii(iino- is |,Mio. .,11,1 |)i-,,.,,| s.. .. . r • 1 

419. The Round Barn Framp 'V\, 




21 



:542 



will Ml I li(* hiirii i-i iii;i<lr i-vliii(lric;il in Iomii .iihI I lie si iiddiii}^ 
S('l. ii|)(iii III"' circiiiii Icrriicc 1)1 ;i, cii'cli' ;is r('|)r('sciit('i| iii 
'ri«;s I IS :iii(| I l:>. Ill lliis Ivpc ..f li;ii-|i iKil oiilv is lli(> 
.siiiiillcsl iiiiinlx r of sIikMiiiv ii'(|ii i red lo forin llic (Milcr 




I'm; I I!i .Sliciwliiu rrniiic ninl yciii'riil |>laii «\ ii <■> iliiilrirjil l):irn. A, 
ili-lvrwiivM licliliiil ciiillr- n, r I iill.'.v; ( '. |p|,i H'.pnus I'.ir rnillc. 



|):irl of Ihr rr:iiiic lull siii;illrr si/.cs ciin Iw used, lor llu! 

I'cjisoii lliiil cNcrv Ixcird in llir sidiiii; is ;i |H)rli t :i li()(>|> 

wliicli iiiiikrs s|)r<'!idiiii;' iiii|M)ssilil(', wliilc :il I lie s;ini»' tini(? 
\\\('\ Jirc iircliccl iii^ninsl llir wind :iiid l;ikc ils |>ccssnre willi 
11 cnisliiii^' si rcss. 

Willi l)!inis uf lliis lv|»(' L*\l slnddiiii;' scl li feci jip.irt, 
li;i\r !iiii|>lf slrcni;lli I'nr :il| diiiinclrrs n|> lo 1<> feci :ind li\(> 
sl.ilddini;' is l;iruv cnoiiiili for Iciriis |(> lo 100 feci in diaiii- 
vlvv. , : , .1 



un 



ciiAi'Ti-;!; xvii. 

WARMTH, LIGHT AND VENTILATION. 

CO.N'rii'ol, (>]■ risM I'lsKATIlKK. 

Tlic life ;icli\ilics iiiiiiii fcslcd in llic ;iiiiiii;il Ixxly involve 
I lie. <-i)n!l innons ni;ii nl< niinrc ul ;i liiiin ul clicniKMl <'ii:in^'('S 
wliif'li ^'i\'<' ri-'" \<> <.i' )ii;iinl;iin llnni. I ln' c cln'mic;!! 

cliiin^'cs, like ;ill oilier-, r;in only licf^in ;il- ;i cfrliiin Icni 
|K'r,'il nrc ; Itclow I hi-, I licv crjisr; wi'l liiii ;i ccrl;! i n i';in;_'<; I Imy 
p> torwiinl ;il n(irni;il i;itt'.-,; iihuN'c llii-, Iciii)hi';i hire itmc- 
lions occur wliidi in|(||Vrc willi llic lilc ;ic'l i\ il ic-, ni;ikiii/^ 
tlicni :ilinoi'ni;i I or c;ni-in^' llicni lo cciisc. 

420. Automatic Control of Temperature. 'I'lic ;uiiin!il 
l)0(|\' is so consi ihilfil 1 1 nil wil Inn ccrlii i n I i mils I lie nornnii 
lcni|icr;il N n • of llic l)o<l\' iiniv l)c n);i i nl ;i i nc<| ;i nloiii;il iciilly, 
i I' onl_\' siilliciciil I'ood i- -ii|»|tl ic<l. II out - iilc <'on(| il i<»nrt uns 
sncli ;is lo lo\c!- iIk' lciii|)i'r;il nrc ol llic l»oi|s' llic ncrvoiis 
Hystciii rciicl-, -cllin^' in o|)cr;ilion ;i Iriiiii ol cliiinf.j.'CH vvliicli 
( \'ol\c lic;il jji-i (iioii'.'li loiiiccl I lie L' renter loss. ir<»n llic 
oIIk r Ininij llic - m rroiind i n;.'' Iein|ii'r;il nrc-, ;irc Ion liiijli iiinl 
llic l)(»(|\- i- liccoinin;.' loo \v;iriii tlic liciil |iro(|iicin;; rcjir 
lions lire iiilii liileil or |(cr'^|»iriiil ion is ^1 iiiiiil;ilc<l lo \-i'i\\n;(\ 
t lie lo(» Iii<^|i lciii|»eriil II r<' liv liriiii.' iii^'- I lie Mood lo l,li(! Hkill, 
wlicrc. llic le|ii))ei;i I lire iiniv l»c lowered liV llic e\'ii|ior;il ion 
of water in iIm' -jiiiic nijinncr llnil llic wel Inilh ol ;i llir^r 
inouK'tei" is cooled l)\' llic |o-- (d li< ;rl wlindi rioc llic work 
ol e\ii|)or;it ion. 

421. Normal Animal Temperatures. '|"|ie noiniid lcni|)(!r- 
iihircs uliicli inii-^t Kc nniinlii ined williin llic ;iiiiin;il hodv 



344 

\;ii'V willi (lillcrciil species of iiiiiiiiiils hut iiiiMnii;' llie uiiriii 
hlooded Idniis llie niiinc is ikiI wide, ;is iiidie;iled in the 
tal)li" IteldW. 

Horso lOO-J-K. to 100. 8"^' F. 

Cattle .. 101.8 to lOi 

Slioop 101. ;< to lO.j.S prt.l.ahl.v KU 6 to 101.4 

Svviiio 100. il tolO:).'! 

Dos ilit..-) tol01,7 

Aiiv iiiiiiked depjirliire iVdiii lliese leiiipenil lires in tlic 
Hiiiiiiiil l»()(l_v, eillier \\\y oi' ddwti, residls in ])li_vsidldiiit'al 
(lisl 111 haiiees \vlii(di injure llie liealtli el' llie animal. 

422. Best Stable Temperature. — The data for a rational 

praeliee .vilh ,'(d'ei-eiiee |o I his poiiil ha\'e _\-et lo he tU'- 
t(M'iiiiiied e.\]H'i'iinenlall_v. At prtsenl rules can he forinii- 
lated only from ii'eneral eonsidera'l ions. 

SIiie(> iiies; d| ihe liodily rnnelions resiill in the iicnei'a- 
tidii (d more or less liea! and since the leiiiipei'al lire must he 
k< pt held A KM) td !(»."» it is clear ihal no aeti\-e animal 
shdiild he surrdnnded hy lemperalnres as hi_i;h as rlie n-or- 
mal lemperatiire of the hdd\. ()ne of the main oh)ects of 
the circniatioii ~>( the hli.od tliron^h the skin is to Idwer its 
teinperal III e Ixdere it reliirns td the interior, so I li.rl those 
parts may he codjed. In diii' case we hecdiiie niicdni fdftahle 
in a. siirroiindinii' tempeialnri miudi ahoxc Ti! ' and I he 
same is line ot onr domestic animals. 

Slahles should then as a rule liaxc a temperature lower 
than 7-' \'\ hill how niiudi innst depend upon cii'cnm- 
stanees. The rii^lil surroiiiidinii' temperature is that which 
will permit the necessary loss of lie;it from the hod\- with 
(Uily the normal rate <d' perspiration. 

Iveasoiiiiii;- Iroiii iicneral piiiiciples it is to he anlicipa'ted 
that aniinals which are heiiisi' fed heavily, like fattening 
s>vine, steers or ^heep, as wtdl as in^ilch co .vs, will do helter 
in somewhal co(der (piarters hecanse ( 1 ) the lariicr activity 
necessary to |ti'odnce the extra assimilalion desire<l would 
dovelo]) more heal wliicdi niiisl he removed fr<iiii tlit hodv, 
and ( 2 ) hecanse ihe aim is lo induce smdi animals lo eat as 



345 

inucli as llicy can (•oiiNcrl ('(•oiiiniiicallv iiiitu llisli ainl milk 
and warm ([nailers ninsi make the demand lur IuimI less. 

Il lias liccn loiiiid willi man llial wlicii las! ini^- and at, rc^rtt 
under a Icmpd'al ii re nl IK* 1'". lie citnsnm'cd IJO,") cnhic. 
iiK'lics (d oxviii'iii |)cr li<iiir, luit under llie saiiilc conditions 
except, a temperail lire (d ")!» I''. I lie amoiiiit of oxy<ieii was 
1 •') per eeni . lii'e.iier and I lie a mi III III il' ca rhon d i oxide i^i ven 
oil" also I.'! per cent, urealer, showing' that a lii^lur ra'l(! of 
coiisuinpl i(iM of lend ill llie hods' was niaiiitaiiied and Jieiici! 
tlial tlie man winild lie re(piiiT(l pi eat more. 

Il is 'Aitli tlie CMW :iiid ralleiiini:' animals as il is willi a 
I liresliiiiii' maeliiiie, il reipiires a liiulier rale of \asle (d 
energy to run llie imudiine ra|)idl_v than it doics to run it, 
slow'ci", hill the sa\in,ii' in time of all employecl i|o inaiia^'e 
the ma(diine more than pa\s lor the i;realer waste. So the, 
cow may reipii"e an extra ainonnl of lood lor tei: perat lire 
maintenance to (,\-ercoiiie the couler ipiarlers hut she is 
likcdy to eat eiioiiiih more food to eiiahle her to make more 
milk and a liiahei- |)i"otit when all items id' expense are taken 
into account. 

With aniniials (,n sim])ly a maintenance ration the aim is 
to cany them with the least anionnt of food and In nee in as 
wai'iii <piarters as will he heallhfnl. 

It seems likely thai! the hest temperature -nrronndin^'s 
lor animals heiiii; crowdecl ,\ill he louiid helweeii 10' and 
50'^ F. and for animals upon mainleiiance rations I roin T)!)'-* 
to Ctr/' or e\(n TO !■". 

423. Heat-Proof Construction Impossible. -Xo ene,loHnr<> 
or hiiildiiii:- can he so constructed that all I h(^ iK'ut it con- 
tains will he pre\'eiited from escaping. If it ]H ko.pt above 
froozin^ through c(d(l winters tliciH^ must be within \\\(i on- 
c'losnrc a source of heat. So, too, no (enclosure or hiiildiii<; 
can be so tlioronf:,hly made as to cxcdnde all heat an<l licnce 
it is impossible to build a ''cool room" whieli will not ^et 
wanner diirinn- the siimmer unless it contains somr- means 
of reimovin<;' the iieat whi(di entei's. 

The out-door root cellar wliieli does not ivcc/A' ilurin^ 



;54(; 

tlif wiiilci' is |)rc\ciil('(l Iroiii doiiio so l>v I lie licjil which 
♦'liters il. thr(»ii^h ithc hothMii. 'V\h' saiiici c'cMiir iliirin^' tlui 
suiiiiiicr <;i"<»\\s j;rii(lii;illv wiiniicr :is thci season jkIvjiju'cb 
iiiid is (iiilv i'('hili\cl V codl Ix't-ausc pari of I he heat ciilerillg 
aboN'c is ('<»ii\'c_v('(l through the lK)(t(tm into the cartli, to re- 
sl(»l•l^ that whii'h k('|)t the ('('Ihir Irdiii frcczini;' dnnii/i,' tho 
^\"illt('l•. The '\';i)'iii slaMc which (hies iml Ircc/.c is kept s<) 
by thci heat of the aiiiinats sheltered, and the waciidy coil- 
stnictcHl ir'itabh' (Hily makes h'ss aiiiiiial iicat ueech'd to main- 
tain the teiii:pei-al iii-e ; I he >.\alls ill I heiiiseh'es :ire iml warm. 
So, too, no <iariieiil however imnh' is in itself i\anii. We 
call it warm when t he loss (d' heat t liroii,i;h il is slow. 

424. Means of Controlling- Temperature. When it is do- 
t^ircid to coiisitriict a room whicdi will he^ waian in winter or 
one wdiicli will he coioij in sniiimer the sanuv ])nnci])les ninst 
bo eni|)loyed in ea(di. In tlu^ tirst caset it is desired to re- 
tain tiiio heat produced in 'the room; in the six'oiid case to 
prevent lioat eoniini;' thron<>li tiie sani(> walls, but from the 
opposito' direction. 

To secni'o either (d' theses (mkIs 'two essentials (d" constrnc- 
tion innsl. be obser\e(l. The walls iimst be as nearly air 
tiji,lit and as |)o(ii- conductors of heal as |»ossible. In the 
conHtnu'tioii (d" a warm house, a. warm stable, a cool i('(i 
house or a, cool curin^i,' room lor (dieese t he ,i;reatest at teiition 
should be ])aid 'to securin*;- air ti^lit walls because, no mat- 
ter how ])oor condni'tors are ]nit into tlu^ walls, if there are 
craeks ahont doors and windows or open joints in the wall, 
the effect of wind ]n*essnre and wind suction will be 'to 
change 'the air in the room so rapitlly that it will be diffi- 
vult to keep il either warm or cold. 

425. Solid Masonry Walls. — Stone basements with solid 
walls are sniliciently warm f(U' stables but they are too good 
conductors (d" heat t<v be snita])lei for dwelliiiii,- ironses in cold 
climates Avhere tin* in>side teni])eraiture must be mamlained 
at 72° V. Hollow brick walls, wlien plastered with a close 
textured mortal-, throui;h wdiicli air cannot ])ass readily, are 



347 

Keller lliiiii s(]|i.| iii;iMiiii'\ liiil ;ii'e iKil ;is wjiriii ;is lliese Well 
(MUiwti'ueted of jtll wood ;tii<l ;^(i(iil l)iiili!iiij^ |);iper. 

All nnjdiislcred brick wall, <>i' a hriek wall plastered with 
(•(larse liiii'( iiiorlar (inl\\ is one of I lie pooi-est wliicli (nill be 
used eillier to relaiii or exclmle lieat. Its porewi are so upon 
lliat the siiiall("it wind pressure (»r wind siic-tioii causes a 
ready ilow of air lliioiii:li cNcry porlion of I lie wall, 
(dian^iiiii tlu^ air ol 'I lie room (|iiickly. 

l^'or cheese ciiri Hi;' rooms, wlieie llie lemperat lire is to bo 
held down by 'iieaiis of cold air diuMs, masonry walls, (weu 
when iiiiade air liulil, are not snitajile because^ they ar(i such 
<i(>od conductors of liea'l and so massive that they tend to 
maintain a nnirorm tem]»eraliire in siiimner somewhat 
hitiher than the mean ol the air outside. 

426. Hollow Masonry Walls.-- -When stone or brick walls 

are miide liolldw they beeoiiie miieli wanner in winter and 
cooler in suninier than vvdien built solid because; the air is a 
niiudi p(MH'er con<liic'toi' of lieat. 'Hie ithicdvuess of tire air 
space is not important and oiie-lialf an iiudi thi<d< is |)ra(i- 
tically as seiwiceable as one of <! iiudies. 

Where- hasciuent or seini-basenient cni'iii<4' rooms for 
clieese are construc'te<l the upper four i'eet of flio wall 
should be niadci with a dead aii- space itic prevent tli(! heat of 
the warm soil as icadily reaeliinn' the interior. So, foo, in 
the casei of dwelling;' lious(« in cold (dimates, whetiier tliey 
have cellars nnder them or no't, it is iini)oi'tant to make the 
n|)|)er ."> or 1 feet of the wall hollow for the reason that the 
cellar will be warmer and hence the lloors under the living 
rooms al)o\'e. 

427. Brick Veneered Walls. — Wlum; brick arc cheap and 
lumber high, walls made of 2x4 studding sheeted inside 
and outside with matched fencing and then veneered with 
brick make a very durable and warm building. The brick 
will not decay and the expense of nails and frequent paints 
ing are avoided. 

It do'Cs not do 'to (le|H iid u|)on the bri(d< for wai'inth, how- 



:U8 

cA'cr; llicv siiiiplv Inkf the phicc ol the ^i(lill^• :iii(l |Kiint. 
WluM'ci llic li(»iis('i is simply sheeted (nilside willi ('(umiioii 
boards and \'eiieei'ed with hi'icU, and then hillu^'d and 
})h>st(M'e(l insi(h", the hnildinii,' will he very cold because the 
wind will iz.'O' easily 1 lii'(iiii;li lire brick ami the cracks in the 
sheetini;'. 

428. All Wood Walls.— Koi- tjie constrnctiou of dwelling 
honses, cdierse ciirini;- rooms abo\'e i;ro\iiid and ice houses 
thei'e is no t\|te ol wall so etlective and so cliea]) in iirst 
covst as the all wood \\:dl w here ij^dod biiildini;' paper is used 
with th'C' hnnber. I'or a dwelliiiii lionse a reasonably warm 
wall is secured >>lien the studding' are sheeted ouiside and 
in with one layer ol toni;ne<l and iiiooNcd fencini;', coxcred 
OiUteide with -!-ply acid and w'aterpriHd' paper and lathecl 
and |)Iasl'ei'ed iusule. The inside sheeting' is wai'iner than 
ba(dv plastei'ini;- and better because it i^ives a miu'e sMvlid 
wall, and lath nia\' be used ou it foi' lurriuii,'. 



ij(inri\o i<Ai;.M itiM lauNos. 

TIk^ lii;lit ini;' of |';irm buildini;s is icipiiied to secni"(\ 
three important obj(Hrts: ( 1) facility in doiui;' work; (2) 
noe('ls of t he animals housed, and ( .'! ) healt lil'ul conditions. 

In the dwelliiiii' house iuu(di care should be exercised to 
secure an ample anrount ol lii^lil in the kitchen, in tlu^ 
diu'inu,' room and especialK' in the main li\'iiiu' rooms. An 
abniulauce of lii;hi| is iieedi'd in the kilidieu not only to 
facilitatx^ the W(U'k l)ut to make the best intentions and 
efForts toward (dea.nlinews more certain. li rei(]uires an 
eifoi't to b(^ i;io()niy and feel ui;ly in the face of a hearty 
blUi>'li, and a brii;ht (dieerfnl nmiii has uiiudi the samei etiect 
upon those who (H'cn|)y it. 

429. Efficiency of Windows. — 'Plu^re are many conditions 
which atf(xit tlici ettici(Mic.y of windows in lighting a build- 



340 

iiij;'. Ticcs or l)iiil(liiii;s iic;ir hv, wliicli coxcf ;i (•(Uisitlcr- 
ilh\o |W)i'li()ii <»l' I lie sky, iiiiiv i-cdiicc I lie lii;lil (■iilvriii<4- ji 
window Very iiiiicli. Alncli more li;^lit coincs iVoiii tlu; 
sky liii^li ;il)o\c I lie liori/oii tli:iii fiom low down :iiid lumco 
a ]>()i'('h <)\-{ r ;i, wiii(K)w cirls out ;i \cry laiiic sliiirc of tlio 
li<i,lit. wlii(di iiii^lit ciiticr it. 

I!iiildiii,<;s wliicdi Iriivc lliick walls r(M|iiii'c lai'o(.r wiii- 
d<nvs to adiiii't the same aiiioinit <d' liiilit; as wonld (Miter 
tlu'ou^'h windows in ijln'ii walls. Uasciiiciit stahlcis with 
heavy stdnc walls rc(|iiii-c laravr windows Ivccaiisc the walls 
nv(t tliick, and so with a Itrick or slonc lionsc. 

WiiKJows lonu' n|i and down adnut nindi more lifj;lit 
than windows of the same dimensions with llicir Uni^ axis 
lioi'i/onilal bccansc nincli nioi'c li^lit, coincs from llic iij)|km' 
jH/rtion ol the sky. So, loo, windows cxlcmlinii from iK^ar 
th(^ cciliiio- lowani tlic Ihior liohi the roum Ixll.cr llian 
when ("..xitcndin^- from near the lloor n|». 

430. Position of Windows.— Li vin<»- rooms and stables 

slionld if |.ossil.lc \)v aiTan,<;cd so that the Ivody of lio'ht 
may come fnini the sontli side wlicrc I lie direct snn.shino 
may cntci' tlic windows. In a dwclliii<;- house in the win- 
<Uh- this IS vcvy iiiiportani liccaiise then the ainoiiiit oi' \i<y[it 
in smallest at hesi and the family niiist he more chxselj 
confined and therefore need the direct, sun tiieii most. For 
ponhry and lor swine soiitli windows arc spotu'ally de- 
sirahle. hariie wiiid(,ws at the south are not. as ohjec- 
tioaiahle for heal in slimmer as miohi ;,t |i,.,,( j,,, jl„,,ii"^lil-, 
becanse the sun is ho hio-h that a lar<;e portion of tlic (Uivvjt 
siinsliine is reljected froni the ojass and j)reA'iented from 
entering' the house; hnt (hirin«>' tlie winter, when.tlio sun is 
low, the advantage wliieli comes from its heating effect as 
well as the lio-ht is very considerahle. 



350 



VENTILATION OF FAEM BUILDINGS. 

Ill tlu' physiological sense air is as iiulispensable to tbo 
cow ami horse as is water, grain, hay or gitiss; so, too, is it 
as essential to the developiui-nit of power ^n the steam 
engine as is the Avater and the fneh It is so abinnknt abont 
ns and we procnre it nsnally so unconsciously that its 
necessity does not occur to us. But when large numbei-s 
of animals are housed together in close stables ample pro- 
A-ision must be made for th'e ingress and egress of air. 

431. Necessity for Ventilation. — The need of ventilating 
dwellings and stables grows out of several conditions: (1) 
Tke consumption of the oxygen which is die essential in- 
gredient; (2) the exhalation from the lungs of carbon 
dioxide, moisture, ammonia, marsh gas ((' II4) and organic 
matter; (8) the accumulation in the air of occupied stables 
and dwellings of bacteria and other micro-organisms as 
well as solid dust particles. 

432. Carbon Dioxide in the Air. — Tliis gas is given off 
from the lung's with each respiration in nearly the same 
ratio that the oxygen is i-einoved, hence air once breathed 
is not only deprive<l of a portion of its oxygen but it is di- 
luted with au equal volume of carbon di(K\ide and is there- 
fore rendered doubly unfit for use again. 

That air once breathed from the lung's is not suited to 
further use can be clearly and forcibly proved by filling 
a quart ]\Iason jar with air from the lungs, by blowing 
through a rubber tube, and then quickly lowering a lighted 
•taper into it, wliich is quickly extinguished, showing that 
the air has lost so much oxygen and gained so much carbon 
dioxide that the taper cannot burn in it. 

433. Moisture from the Lungs and Skin. — The moisture 
taken with the food and as drink must be ag-ain removed 



351 

from the body and a largo portion of it leaves tliroiigli the 
lungs and skin, in the foirm of invisible vapor. If the air 
of a stable or dwelling is not ehanged witli snflHcieiit fre- 
quency it bcK-oines so damp as to intierfere with the proper 
action of the lungs ajid skin in, this respect, and it is im- 
poiitant that the A'entilatiion shoidd be strong enough to 
prevent the air becoming too damp. 

One of th© surest indications of an improperly venti- 
lated stable is the condensation of moisture on ithe walls, 
ceiling and floors. It is sometimes remarked that cement 
floor, and stone basenvents are objectionable because they 
"dra.w moisture," making the air damp. The trutli is the 
stables are insufliciently ventilated and the moieturei from 
the animals condenses upoii the cement floor and stone 
walls simply because these happen to be colder. Instead 
of "drawing" moisiture and making the air damp they have 
exerted exactly the opposite effect by condensing the 
moisture from the air, leaving it diyer than if the con- 
densation had not, occurred. 

434. Ammonia and Organic Matter Removed from the 
Lungs. — When one paeses from the freeh air intoi an occu- 
pied stable or room wlierei the air has been rendered im- 
pure from impei-feot ventilation a depressed feeling and 
offensive odor are recognized and sometimes this effect may 
be so strong as to produce nausea. When these odoirs and 
the odor of ammonia can be detected it is positive proof 
that the air needs changing more rapidly. 

Some of the organic matter given off" from the lungs is 
strictly poisonous and so much so as to produce death in a 
few moments. If a live mouse is kf-pt in a sealed pint fruit 
jar until it is nearly suffocated, as shown by its action, 
another mouse introduced into this jar will die at once, 
wliile the one which vitiated the air may be removed and 
it will apparently recover. It appeare as if the organic 
principle eliminated fi^om one animal is more poisonous 
when breathed by another, even of tlie same kind. 



352 

So jioiistvuDus is tlu' or^anii' priiu'iplc I'iMiuwi^d from 
the lung's tlint Browii-Sociuanl in ISST condonsiMl the 
vapor of cx]>irotl air and injct-tod 1.") ct,'. ol" k. into a rabbit 
wliii'h (Hei(l from tlio offci'ts. Urown StHpianl couisideired 
tlit^ substjini'i'i a volatilv alkaloid scH'rotod b_v \\\v Inno-s. 

Water standing over night in a jHutrlv viMitilaitcd room 
or sta.blo comos to lia\H' a Ncrv disagrt'cabU^ taslo fruin tlio 
absorption of impurities from the air and ihis is oiui of the 
luotst serious objections to keoi)ing water standing in the 
stable for cows or o'th'er animals. 

435. Micro-organisms and Dust in the Air. — It has long 
l)(HMi reeogni/ed that th(> air of old and pooidv \'eirtilat(Hl 
liouses, espeoially if they are not ke|)t tdean, contains 
many mo'rc>< dust pai'tiides, spores and nui-ro-orgunisms 
than newer and bettcn* ventilated housi's do. The' same 
must bo tru(> also oi' stables but in a higher degree. 'Idio 
anunmt of (\\\>t and of organisms as well is almost always 
morei abundant in oeeujvied rooms than in the optMi air. 
This W(ndd bo ex])eeted both beeause of the slowing down 
of air uu)vemH'nts after entering tlu' honse, whiidi acts 
exaeitly like a silt basin in a. line ni' tile, and beeanse (d' 
their |)rodnetion there from \ai'ions eanses. 

Strong ventihition tends to remoxc these organisms and 
duiit ])a,rtieles with tiu^' aii* from the eomjvartmients and 
this is the rational basis t'or airing a txMlroom or any other 
after sweeping. Tlu^ air has Ixn-n tilled with l)oth sets o( 
im})nritieis and opening 'the windows or using any other 
means (d" prodneing a strong euncnt will help to eh'iar tho 
room. 

436. Bad Ventilation Predisposes to Disease.— The most 
helpful health rule whieh man am adopt for himself or 
for his donu\stic animals is to avoid whatevcM- tendi^ to 
wealcen the system and to take a.lvantage of whatever 
tends to greaiter vigor. 



353 

It hluiiiM l)c clciiilv icicofiTiizcd tiiiit tlic gcnriK of dipli- 
llicria. (/t t iilicrciilosis, \\<}<^ cliolci'ii and other (;<jntagioiis 
(liscM.sc's arc liiiltic to he met vvi'th alnujwt any day and in 
any |)lacc and iliat •.vlicrcx'cr a projtcr breeding' j)hu'(' intiy 
be found tlic disease is lial)le tu i-tai-t and from it spread by 
force of ^Tcater niunbcrs oi' <icnns. 

Wliile then fore llie inicr<j-()r<ianisMis usually found in 
ji;r<atest nunihers in du>ty lious<'s and stables jxjorly venti- 
lated and eared for are not in tlieniselves a source of dan- 
ger, tlic I'lin-down, weakened condition which poor ventila- 
tion is sure to engender will certainly tend to start a case 
of contagious disease and tlien, witli greater nujnbers of 
gerins in the air to be introduce*] into the system, animals 
of greater vigor niu.-t sueeund) to the-e irn'isible^ fow be- 
cause of th;ii- vast nuinhei-. 

Ain]>l( vent ilal ion then -lionld a'.\a_\-s lie seeui'e(l, jirst, 
as an indispensible condition f(»i- maintaining flie power 
to resist disease, and second, in case of disease, to botli clear 
file ail- and to give '|-he animals an o|»j)()irtiinity to defend 
tli( tn-('l\'('s against, this type of foe. 

437. Amount of Air Respired. -'J'he amount of air ordi- 
narily taken into and put out of the lungs by man. witli 
eaeli respiration is gi\'en by different observers as follows: 

"«i"l)st 20 - HO cubic iricties 

Valentin 14 - 92 cubic inches 

Vierordt 10 - 42 cubic inclies 

Coatlinpf! 16 cubic incites 

llntcliin.son 16 - 20 cubic inches 

A vcraKP 15.'i _ 46 cubic inches 

or an a\-eiage of about .".0 cidiic inidies. 

Tlie auKMint oi pure air whicdi must be breathed in order 
to supply It he (hxvgcn needed by different animals, (h'duced 
ironi ('olin's table, is given below: 



354 





Air Breathed in 
24 Hours. 


Oxygen Consumed in 

24 BOURS. 


Animal. 


Per 1,900 
lbs. of 
\vt>ight. 


Per lie'>d. 


Per 1,000 
lbs. of 
weight. 


Per head. 




cu. ft. 
2,833 
3,401 
2,601 
7,353 
7,259 
8,278 


cu. ft. 

425 

3,101 

2,804 

1,103 

726 

21.84 


lbs. 

12.207 

13.272 

11.01 

29.698 

29.314 

21.84 


lbs. 
1.831 




13.272 


Cow 


11.04 




4.4!>6 




2 931 


Hen 


.075 







438. Amount of Air Used Compared with Feed and 
Water. — A 1,000-pound cow requires daily tlie equivalent 
of about 30 lbs. oi liav and iirain and 70 ll>s. of water or, 
in round nunibei's, 100 1K<. })or head and per day of solid 
and liquid food. 

A cubic foot of air weii;lis about .OS lbs. lieiiee, from 
the table in (437) , avc have 

2804 X -08 lbs. = 22i.32 lbs. 

which shows that a cow needs to be sup]>lied with twiee 
the wedg'hit of pure air that she chiew of food and water eoin- 
bined. 

439. Degree of Impurity of Air Permissible. — We are yet 

"Without sutheiontly exaet (hita. t(^ permit this problem to 
be concisely stated for stables used for doinestic animals. 
In absence of exact data and in view of the unavoidable 
leakag'e of air through the walls and about windows and 
dooi-s we have arbitrarily assumed that if the air is ch.inged 
in the stable ait such a rate that it at all times contains no 
more than 3.3 per cent, of air once breathe<l fairly good 
ventilation would be ]>rovided. 



440. Rate of Supply of Air to Stablas. — On the basis of 
(439) the number of cubic feet of air per head and per 



355 



hour, iisiuu' tlic (l;it;i in rlic r.-iMc of (437), wonld ])e as 
sfated helow: 

For liorses 4,296 cii. ft. per liour per head. 

For cows 3,542 cu. ft. per liour per head. 

For swine 1,:-I92 cu. ft. per hour per head. 

For sheep .... 917 cu. ft. per hour per liead. 

For hens HI .4 cu. ft. j)Pr hour t)er liead. 




Fifi. I30. — Simph'st method of takiuff air into .'<tone or basement sta1)I('. 
A B and A B show where the aii' enters. These tlues may be made 
out of ordinary 5 or 6 inch stove pipe witli eil)ow, or j^alvauized iron 
I'onductor pipe, or tlie pi])t' tlirmiL'li w.ill nia.\' be ordinary 5 imdi 
drain tile, with stove pipe and elliow on inside, or the flue may be 
made of 6 incli fencinji. 

TJio .vt'iglits liere assmiUMl are 1,()()() lbs. for the horse 
and cow, 150 lbs. for the hog, 100 lbs. for sheep and 3 lbs. 
for the hen. With different wei<ihts the amounts would 
chang-e somewhat in proportion io the size of the animals. 



441. Capacity of Ventilating Flues.— With the data in the 
last section, and the number of animals to be provided with 
air, the capacity of ventilating flues should be such as to 
en-sure an air ni(»vtment etjual the rate given in the tabh; 
of (440). Tt is practicable to construct ventilating flues 
tlirfMigh vhicli the air from stables will travel af the rate 
of 200 'to .lOO feet jver minute without mechanical forcing 
or the aid of heat, other tliaii that derived from the ani- 
mals in the stable. 

AVith a ventilating flue 2.\2 fed. inside mea.sure 20 cows 
would be su|)|)lied when the cuiTent in the flue wa.s at the 
rate of 2!t5 feet jx-r minute. At this rate 40 cows would 



356 



need Iw'o llin's 1.'n2 I'ccI inside iiik'nsiirc ; (>() cous llii'cc; 
SO COW'S t'diii' ;iii(l 100 ('(iws li\(\ 




If'lt!. ir>l.— M()(ll(\fiill('ii of KIk. ino wlicri' 111! tln> rl^lit :i notch Is left In 
tlic Willi wluMl luilldliif;, so lluil the line rises llnsli with the Inside 
of the Willi. While on the iel'l side the line is shown l>nllt In llie wiill. 
Tills niji.v be done by biilldinn iiroiiiid :> inch driiln llie or iironiid n 
Iio\ iiKlde (it tciu-ilij;-. 

442. Cubic Feet of Space in Stable per Animal. — Tt has 

Ih'cii iMisjiiiiiiii'v Willi s;iiiil;iiv cniiinccrs in jilannini;' liospi- 
liils, pi'isins. sciauil rcuiins. ('(c, to all(.\\" so niaiiv ciiliic 
i'cvi of spare |iei' (U'eii|iaiil , ImiI llie nniiilier ('liosen lias not 




Kju. ir>2.-Melhod of liiktnjr iilr Into a lumk burn on the np-hlll or bank 
side. 'riu> iilr line Is niiide In llie siinie wiiy iis descrlbi'd In I'Mji's. 150 
1111(1 LM, lint oil (lie outside has its end covered as reiiresented at A 
on the lelt with a leiii,'lli of (I or S Inch sewer tile witli Us top cov- 
ered with a cap of coarse wire screen, Praln tile wonid not answer 
f(M- the outside e\|iisiire at the surface \<( the ground as trosi woiihl 
cause it to cruiiiblc. Wood could lie used and replace<l after nvlliiif; 
has occurred. 



been to siippl v I lie propi>i- aiiioiint of air Itiit ratiuT to axoid 
(Iratls loo <ti'0!ii; for health ami eoiiijoi'l. 

It shoiihl ln' distiiu'lh' stated tlial in niatteis of \-entila- 



357 



lion it i^ ciihic h'cl ot ;iir rnllicr lli:iii ciiliic feel ol" s|)iicc 
Avliicli slidiild \)r |)i'<)\i(|('(|, mid in t lie consi nici ion of stables 
tlu^ iimonnt of space nce(| he onlv so nincli as is i'e(iiiir(3<l to 
penult ain|)le I'ooni and freedom lo care f(»r the aiiiimily. 




I<l<J. 1;),1- Two iiictlKids oC viMitihiliiij.' ji (l;iirv luirii. On Die left llic viMl- 
tlJiUiiiji line I) K rises sliMiuliI Iroiii tlic llnor. |.;issiii« out IIii-diikIi 
llic nior iinil risiii- .-iIkivc I lie ri(l;c<'. One. tw„. i<v llircc iif llicsc 
would lie used ;icc(jr<liiiir lo iiiinilicr of <'mIIIc. TIic Hues should lie al 
one or llic oilier side oT llie eii|i<d.'i riillier tliiiii lieliirid il. On I Im> 
elt (' K represenls liow ;, li;i.\ sliool nui.v lie nsed also for veiilllalin;? 
line. Ill eaeli of tlM^se eases (lie veiil llallni,' fine would laki" llie jilaee 
ol one cow. 'I'his method would -ive llie I.esI vent ila I ion linl has 
thi- olMcelloii (d oeeiiiiyiii};- valuable s|)aee. ( ', In llie Iced shoot, is 
a door wlii(di swiiius oiil wIk'Ii hay is I.eiiiK thrown down, hnl is 
elosed when used as a venlllalor. the door not rea(diiiiK (iiilte Ir) the 
lloor. lo take air into this slal.li. iC il is liiiill of wood wll h slnddlliir 
o|'«'iilMKS wonid he lell at A aooni 1x12 in.'lies •■very tw(dve to six- 
leeii leel. and the air wonhl enhr and rise l.et wi'on the she.diiiL' 
ol he insi.le and the siding; on Hie oiiiside, .Mil .m-Iiik at I', as renr.- 
seiiled l,y I he arrows. If llie harn is a lusenient or stoii<. stnietun; 
the air inl.-ilies eoiild be such .-.s .lescribed in (i;;nres KH, Ifd and 152 



1 weiitv cows sliould not lie lioiised in a space iniicli less 
tliaii 2Sx:{:} feet, Avilli cci linos S feet in tlie clear. Tti 
warm (dimates there is no ohjcctioii, exce|)t tin; mutter of 
cost, lo hio-h stahles, hut whei-e it is cold liioji ceilings pcr- 



22 



358 

luit the warm aiv to rise so far ahovo tlio animnk as to leave 
tlio 8t<)l)le eoh! at tlie tloor. 

443. Forces Which Produce Ventilation. 'V\w iiiovemeut 
ot" air (Mirrciiis into ami fi'oiii a xciit ilaled sialilc^ is caused 

1. .l)_v the wind pri'ssurc ai;aiiisi \\\v huiltliiii;' teiulini:; to 
foree air into the stahh'. 

•2. \\y wiiul siu'ticii i>ii the leeward side of the stable 
teiuliiiii' ti> draw air (Uil. 

->. H_v as]>iratiou aeross ihc idp ot" the Ncniilator. 

1. \\\ the ditVereiiee in h'liiiu'rature hi'twei'U the air 
in the stahle and t hat oul-idc. 

When llic wind i< iilnwini; auainst a Iniildinu' ihere is an 
increase of pressuri' al>o\i' that inside which forces air into 
the stable throuiih any available oj^eninii' and then out 
aiiain on the o[)|>osite side or np the ventilating tltie. At 
the same time theie is a low pressnie on the lee side which 
tends to draw air ihionuh any (i|)( nings on that side. 

Where the ventilator i i<es above the roof as a chimney 
(hies the movement of air acros-^ its top |n'odnces a di- 
minished piessuie and ihe air is aspiiated out on the prin- 
cijdo of the aspiiator ns( d on perfumery bottles. 

The dift'erence of temperature causes a ditl'ereiu'e of 
pressure b(H'aus(> of the expansion making the air in the 
stabh^ relatividy lighter than that outside; anil the hmger 
the chimney or veutihiting flue tlie stronger Avill l>e the 
draft, b(^th froui difference of tiMup(>rature and the aspi- 
ration across the to]i of the chimney. 

444. Essential Features of a Ventilating- Flue. — A i>ood 

ventilating line must have all of the characteristics ])os- 
sessod by a good chimney. it should be constructed with 
air-tiglit walls s(» that no air can enter except from the 
stable. It should rise abovi' the highest porticui of the 
roof so as to get the full force of the wind. It should be 
as mnirly straight as ])racticable and should havi' an ample 
eross section. Stronger currents through the ventilators 



359 



will 1)0 secured Uy iiiakiiii:' one <tr a few largo oiu^ than 
where many small ones are ])r<ivi(le<l, and it is usually best 




r;. 154.— Scconrl 1..'.- 
coiiK's ill as (Ic-i, 
Olio or iiiort' vfin 
iiiK out IlirouKli 
flues if ilic Icnii 
secure tlie li},'liti'i 
I)lac(,' the studdiii] 
ho that a wiiltli 
tvheels of tliis ii;e 
ail air-titrht tliie. 
the sidiiijr. On t 
the harn above in 
shielil to i)re\eiit 
to carry thi' 11 ik 
l)hite, and thi ai 
seliled. howevci'. 
dinjr used tir Ih 
he iirovidcd f(ir. 



st method of ventiiatinj^ an onliiiary harii. Tlit,' air 
■riiieil in the cither (inures, and passes out tlirouj^b 
ilators risiiij; a^raiiist the side of the tiarn and pass- 
ilie roof. :[•■■ represente<l at A e' K. To iiialte tliese 

is a balloon frame, the best metliod would lie to 
■it jralvaiii/.i'd iron in eijrlit or t<'n foot leii;rtlis, and 
Lt \ili('i-e tile Hues are to be, the ri^lit ilistanec! apart, 
of Ihc nielal covers the space bet ween two stuils. 
lal ii.iiled on ojiposite fa<-es of the stud would make 

On the outside, this metal would lie covered witll 
he inside in the stable, with the slieetin>ir. but in 
itliiii^ would be needed exceiit perhaps an occasional 

the li;'y from <-nishiiitf it in. If it is not desired 
'S through the ro<f, they may enil just bcdow the 
r pass cut tlirou^rh the cupola, 'i'lie method repre- 
would «ive the stron^'est ilraft. The widtii of stud- 
e tine would vary with the number of animals to 



to have as few as praetical)lf and not leave the air impure 
in distant j)arts of the staMe. 



445. Location of Ventilator. — The best location for the 
ventilatina' -liaft !■- near 'the center of the stable where 



360 



siicli a position Avill not intcvfovc with the work. It is not 
often tlmt this i)osition can bo ntilized, and wlien it can- 




KiG. 155.— AltKlitication of Vig. 157. wlicro tlio nir passes straifiht out 
tUnius'li tlu- roof, iusto.-ui of lu'iiijr carried in and out tliroujih the 
ridy-e of tile roof. Tliis lu-lluid would .i;ivo :i stvoiiuer current, un- 
less the veiuilni.ir i>;isses straight down to the lh>or lictween the cows, 
as r.'prcsciiicd iu l''ii;. l.'ui, 

not it niav hv loeatod in varions placc-s, as indicated in 
Fiiis. J:>;!"to IGO. 



446. Openings to the Ventilator. — The ventilator should 
reach to the stable lioor so that air may enter tlie shaft 
frtnn that level. This is very important because: (1) The 
animals not only st-and and lie Ioav doAvn but are so consti- 
tnt(Ml as to breathe the impurities directly to the floor where 



361 



the carbon dioxide tends to remain, because it is heavier 
than the rest of tli(3 air in the staljlo, oven althoufich its 
h'inporatnro is hi<2,hor. 





I'm;. 156".— Ucprcseiiis a inethoil of carrying the flues up the sides ami 
then along under the roof between the rafters, so as to reach the 
ridge either under tiic cupola, or at otlier phices on either side. 
Such a flue couhl lie made very tight, ]>y nailing the light galvanized 
iron on the outside' and inside of studding, and rafters, having a 
suflicienf width to give tlie proper capacity for the ventiliiting flues, 
.•ind siu-h a system of veniilalion would v^'orl< fairly well l)Ut could 
not b(! expected to do as efl'ectlve service as the methods shown 
in Figs. J.5.S, 154, 158 and 159. 

(2) The cohlest air is at the floor and the warmest at 
the ceiling and it is the cold air which should be removed 
during- tlic vvint<'r rather 'than the warm. 

There should be an ojxjning provided at the ceiling for 
warm air to escape when the stable is too warm and when 
it is desired to force the ventilation at the expense of the 
heat developed by the animals. 

Both of these openings should be provided with regu- 
lating valves so that either or boith may be partly or com- 
pletely closed. 



:k»2 



447. Entrance for Fresh Air. — WIumi a sliihlc has been 

iiiiidc close and warm, rciiiiiiiiii; altciilKHi to \fiil ilat ioii, 
|>r(i\isi(iii iiiiisit lie matic ItH' air to ciilcr I lie stable as well 
as to lea\c it. Tliis iii;iv best be doiK' as represeiltecl in 

Fiiis. I. Ml i:.;; Mud ms ic.o. 




11. I,')?. — Slu)WS iinMllod oC vciil lliidii;'' nil <ir(liii:ir\ liarii. where the iii. 
Is liiki'ii out of the slalilc lliroii;;!! IIm(>s l)iilll bclwccn llic sHi..(liiif; 
iin(i_ I't'i wcfii till' .jdisls of llu> f'.illii);, llic iilr IIh'ii rlsinu, lliri>ii};li 
vi'iii lint liiK slml'ts, iiiiulc iiKiil'i^'l <>r iis n |i!\r( of one or more uf llic 
inirl'iiio posts, 'riic air outers Jil A A 1111(1 li. followiiin- llie arrows 
ami passing- out aloiij; Hie Hues (' 1> K. These ventilators, if do- 
slred, eaii lie earrled out slralKli' tl)roii;;li the roof, or may he tor- 
lillii.'lled Inside under the purllne iilale. or iis represeiitcMl In tlio 
lljrure. The I'ross seellon at the rl};lit shows how L'xlL'"s and I'xii's 
may bo nailed tou'ether and placed so as to eonstltute a pnrllne 
post, and at th(> same time a ventilating lliu>. The two sides of the 
pnrllne post or \ out Hat In;; line are represtMiled closed with sheets 
of yah itiil'/.ed iron. 'I'liey may also ho closed with well seasoned 
in.'itchtMl lloorln;^-. The nninher of lieiids nect'ssarv In this plan is 
;in object ion. as tlu'v Interfere with the drjifl m<M-e (M- less. 



Ill all of tlieM"! eascvs it will be noted that the I'resh air 
eiiteis at. llie (•(>iliiii>'. Tliis is I'oi- the purpose of iiiiiii;linii 
it with the wanuesl air (d' the stable so as to I'aist' its f(>iii 



;;i;:; 



]i('i'!il lire iHfdic il fulls lo llic lluor. Ill lliifl vviiy IIm' li<';it, 
wliicli i-. w.isliiiii ;il I lie cciliiiL' i-; s;i\<'il iiiid liii" iiiiliiifils 
•.[Vi- |H(\ciiI(m| fidiii jviiij^- ill cidd ;iir. 

I 'ro\isi(iii is rnrllicr iii;ii|f Inr llic ;iir lo cuter llici iiiliikcs 
(ill'lsi<l(' ;il ;i (iislillii'c nf ;; n\- more Icci] hcinw llic ccilillf;' SO 
iis |(» |)i('\( III llic \\;iriii ;iir Ikmii.'/ <Ii';i\\ii <miI ;iI lllc^'(■ phiccs 
l»_v siicliMii (ir Id |i;i>s dill ilircrllv ;is il woiilil il llicv (jpciicd 
dircc'l l\' I lii'iiii;j II llic \\;il Is. 

Tlicsc ii|ic!iiliiis slidlllil lie phici'd (III ;ill sides <il \\\(' 
st;il»lc if |Hissililc so ;is In l;ikc ;i(l \;i iilnuc cf llic wind pi'cs- 
HWvr :il III! liiiies in i iicre;isi lit: llic diMfl. Il is licMcr lo 
]i;i\'c iii;iiiv siiiiii! opeiiiii;;s lliiiii n few liir^(! oiicH licciiiiso 
lliccdid ;iir i-^ licllcr disi rilMilcij, IcJisciiiiiji; driif'ts. 

448. Construction of the Ventilators. TIki jicsl, fonii of 
veiil i l;il iiiL' llni' is lli:il represeiiled ill I'ii;'. I (JO, iii;mI(;' of 
p,iil\;iiii/cd ii'dii ill c\ I iiid rie;il I'di'iii. A iidl liei- ^'ood fonii '\H 



rfT 



V 




it 



-y 




i--. 



|t'l<; li>.S. .McIIkiiI of vciillliilliiK II Iciinld Htiililc. 'I'llc iilr i'IiI<th iih ri'p 
n>Hi'iilc(l h.v IIk- MiTdWH III \ V, mill jiiimmch mil IIicoukIi n Hue liiilll 
Mil llii- liiHiil*- of iiH> ii)hIkIiI or iiiiilii liiini. Tills Miic iniiv iIhc ill 
rcclly lliidiiKli Ilii- roiil. or II iiiiiy ciiij iil !■; iih hIiovmi In ilic IlKiin-, 
lli<> iilr piiMHiiiK lliriiiiKli II ciiiiolii. II llic ii|(iIkIiI liiiiii liiiH II lull 
Nioii rniiiic, llii'ii III)- Hiincc hflwi'iMi llic hI iidilliii; roiilij he hhi-iI 

ilH VCllllllllllll,' IlllCM III ||||> HilllK' IIIIIMIK'I- IIM (IcK.ll llOll III I'"Ik. IM. 

'I'llI'MC lll'CH < Irl I,,, liiiolr lltihtrr Im .•oM'IIIK IiimI.I.' mill oiil on Hit; 

Hliidillnt,'. Willi till- ll).-lil<-Hl -!iImiiiI/,.'(| iron. 



^CA 



r(i|>c((S(Mil('(l in I'^ii;'. IT)?, wlicrc tlic sides iii'c iilso jiiiidc of 
^iilviiiii/cd iron. 

As a subslitnlc I'oi- ,i;alv:ini/.cd ii'oii in lliis fofiii (v|' \(>n- 
tilatin^' fhu> a pxxl roolini; papci' may l»o used, h\w\\ as tlic 
riihci'oid i-oofinn' made I)v lli(>. Slandnrd Paint Coinj)any. 



449. Ventilation of Basement Stables. Tlioro is a jjjcnoral 
ini|H'('ssi(in tliat hascincn'r slnMcs nrc necessarily nnlicallh- 
ful. 'I'liis idea lias <i,'n)\vn (Uit of tlie fact that il lias hern 
])()vKsil>le In niak'(^ these slahles nineh closer and wanner 
lliaii ordinary over i^ronnd foi-nis, and wIk re ample \-ent.i- 
la,ti(»M. has nol heen proxided they have heen dam|) and 
cliKst^ 







Kia. I.W. Mcllmd of vciil llnlliit; a Imrn wlicro n silo or ;rraiiiir.v occupies 
llic cciilnil iMirlloii. 'riic nil- ciilcrs jil A I! iiikI IIic vciililjitliif;' lines 
lin> I lie spiiccs l.clwccii (In- sludilinj; wlilcll I'onii (lie wiills of llio 
silo, or ollit-r siniiliirc. 'I'lic iilr ciil crliij; ,il (" In i.|ifiilii«s Icl'l nil 

liroUIKl tin- silo. Mini piissiim out Ml 1» Ml till' |o|l. 

Where hasemeiit slahles are well liohicd and propcM'ly 
venlilalcd there is no ohject ion to them on sanitary 
^i'(Hinds and they have many points in their favor wliero 
tlio (H)iidifions admit of their heini!,' easily constrnct(Hl. 
M(^tli(>ds of introdiicino' the ;iir into these stahles are repro- 
soiited in I'^ius. I.")!) to 1,')!*. 



365 




Cic. 1(W.- Is ji section iiC I he cow stiihlc of I lie dairy li:irii ill llic Wis- 
consin lO.vpcrinicnl Slalioii. A sinulc vcnl ilal iii^' line I) I-: rises al)ovL' 
the root' of till- main liarn. and is divided Ixdow tlie roof into two 

iirnis A M I>, wiiicli terminate at or m'ar liie ievel <d' tin* staliie lloor 
lit A A. 'I'iH'se openings are provideii willi ordinai'y rcKlstcrs, willi 
valves to 1 pened and closeti wln-n desiroi. Two otiier ventilators 

rtre idaced at 1! I", to lie nsed wlitii I iie sliiide Is loo warm. l)ill 
arc pi-o\ided Willi valves to lie closed at oilier limes. C Is a dl- 
recf 12-liicli ventilator leaditi},' into the main siiaft, and openinj; 

from tlie i-eiiin«, so as to admit a current of warm all- at all limes 
to tlie main sliaft to help force the draft. This veiililat Imk shaft Ih 
made of KJilvani'/.cd Iron. Ilie upper iiorlion hidiiK ■'! feel in diameter. 
The covcrin;; on I he .lUlsidc is simply for :! rcliil eel oral eflcTl. 



'M\C> 



ClIAPTKR Win. 
PRINCIPLES OF CONSTRUCTION. 

KKI.ATIO.X Ol' ('(i\ i:i;l .\<J I'o SI'ACK KNCLOSKO. 

The- tirst cds'l <p|' :i Imi Idiii^, w licii cxiirc-^scil in Ici-iiis <»f 
cubic* feet ciiclnscd, is iiilluciiccd iimcli liv ils relative di- 
Itieiisieiis. 



450. Relation of Walls to Floor Space. — The form of floor 

sijju'o whitdi can Itc eiude-cd liv the siiiidlesi iiinoiint of wall 
is iieirele, and V\iX- K'l rcpi'eseiils e(|nal anKtiiiits of floor 
sjvace en(d<ised 1)\- the eircde, the S(iiiaie and flie ohloiii;'. 
It" 'the cinde enehiscs a lloer space (d' 1, (')(«» scpiai'e feel the 
leiiiitli (d' the ontsich' wall will he altout 1415.7 fcii't; the 
sipiare woidd then he l(K !(• feet and ha\'e 1 (iO feet of out- 
side wall; while the ehlenu wenid l»e 'JOxSO t'eet and ha\'e 
an (nrlside wall (d' iMMI feet. 




144(1. ICIMI 200 ft. 

I<'|(:. |i:i. Shows c(|iimI tiri'Ms ciicIcimiI liy llirci- lypcs iiC Wiills. 

'Idle s(piare wliieh entdoses the same floor space as a 
ciride re(piires 1 1.44 per cent. iii<»re wall, wdiilo flu^ oblong 
wlioise lenii'th is twice the breadth re(iuii'es iiearlv 40 ])er 
colli, more wall. This means that 10 |ier cent, more siding, 
more nails ami more paint wetdd he recpiired 'to coxcr an 



8f)7 



iilildiiii iMiililiii^, win i( llic length is twice llic width, tliiiii 
would 1)1' i('(|iiii<'d l(ir ii ciicnlnr oiic ciKdosiiif^ tli(^ hhiuc 
li(i(ir s|)}ic('. 

( 'iiiipiii iii^ tlic >(|iiiii(' willi tlic oMdiii;' l)iiildin<i,' it rc- 
(|iiin'.s 25 per (X'lit. loss wall to enclose it. Fro)n tliose rela- 
tions if is (dciii- tiiiit wlici'cvci- it is pi'iictic.ablo to avo'id long 
Hill row l(iiildiiii;s tlicrc will he not only a saving in niatx'r- 
ials hut tlic l)iiildings Jiiay more easily be kept warm in 
winter and cool in sninmer, and in the case of silos there 
will he less loss of" silaii'C!. 




D HARNESS CASr 
S SHOOTS 
H HrORANTS 




(■■|<;. Ii;2. Showllij,' Die s;iiTic cdii vcliii'liccs In I \\ci l.\| 



if liorsL' Imnis. 



In P^ig. 1<)2 are represented two plans for horse barns 
)>roviding nearly idcnticjij accoanniodations. The longer one 
is 105 feet 10 inch(;s in length, 30 feet wide with 18 foot 
poHts. The second is 75 feet 10 incliet^ x 44 feet and re- 
• piircH over S p( r cent, less wall and over )K'r cicnt. less 
Hoor spacx."'. 



451. Relation of Hight to Capacity. — In the building of 
barns, silos, ic(^ houses, giain bins and root cellars the 
more depth or higlut which can be secured the larger will 



368 



1>(> the cjipiicity ill pi'dportiinii to rdnt, cciliiii; or tloor. The 
Muitcrial for lloorin^' luid rootini;' ii low l)iiil(liii<;- is usuiilly 
no l(>ss tli'iiii is i"('<iuii"(Ml for Ji lii,i;li huildiiiii;' niid yv<\ the 
(Mihic contents jirc in the r;ii|io ot' llicir depth. 

In the case of \\i\\ hai'iis iind sihis the ea|)iii'itie« iiicrease 
nuu'h faster tlian the hi_i2,ht heeansie with greater dejjith of 
matenal it is eoinpret=.S'(Ml and on this account i;i-eater stor 
ag(^ (^apaci'ty in soenred. 



7r>/r// OnlM(l( Snrfaas. LAcess of floor ywc 



Jboire J 



"mX87 



D IGOA^ 
B ZOZiO 
C 3.)83/< 

loUd FloornSpace 
J 5U63g/l 
B 66 /C J\lon C 

C /I/34 3ll9X3i9 

1)13300 ■ ^^ 



Hound Baf/i 

Abo\r> B 




^0150 
10 



A 

CZ) 



40/35 
/4 



5Gxmm^ 



Ig \5omii^ 



18 



18 



/4 



96 X5A 
10 



30X30 

zo 



40X4(Ji 
ZO 



^C 




li'id. 1 ? I»in>;niiii nIiowIii^' llic (•(iiiipnrsil lvt> otitsldo surface and amoiiiil 
of kl»M)r space in four sets of barns represented in l'M;rs. 1(>4. Itlfi, It;*', 
an ' U>i. 



369 








^0 



452. Combined and Separate Construction. — The amount 
of capital required to build and inaiutaiu in repair a large 
number of small buildings, is gioater tlian that required 
for a single consolidated structure providing like accommo- 
dations. This is clearly illuetratod by the conqiarative 
chart, Fig. 163, which represents the relations of build- 
ings shown in Figs. 164, 165, 166, 167. 

Taking the cylindrical barn as a standard of compari- 
son, it provides shelter for US c(t\vs and 10 horses, contains 
a -400 ton silo, a granary 16x40 feet, a tool space 16x40 
and storage capacity for all the hay needed ; and yet its 
roof and side area is only 261) ft ct more than the group of 
buildings in Fig. 165, which shelters only 37 cows and 15 
horses, has no sib>, no tool house and not enough s})ace for 
liav. 




Fio. 16G.— Gi-oiip nf luiildiiiss wlii-h shclW'j- 114 



and S li()i> 



Comparing with the 1)uildings of Fig. 166, their aggre^ 
gate outside surface exceeds that of the standard l)v an 



o i i 



area ()4.\<)4 tVn-t and yet they j)r(ivi(l(' ciMiiijx'il (juarters for 
(tnlv 114 cows ami S hdrs-es. 




Kic. Iti" — 'liDiiji ol" ImiMiiiiis ^\lli(•ll sliclicr 1^4 cows and 14 Ikh-scs Avith 
ti)oI liuusi- aiid granary. 

In the group of buildings shown in Fig. IGT, there is an 
aggregaite outside surface exceeding that of the round barn 
by 140x140 feet, or more than twice, and they have less 
floor space by an area of nearly 40x40 feet, and the group 
of buildings shelters but 36 more cows and 4 more horses. 
In this last group the buildings are both low and narrow, 
causing exitreme wastefulness of lumber. 



ta 




168.^ 



<l typ 



>f Iiani .-■Iiowiim- ili-i\. 



111(1 and 



372 



453. Saving of Labor. — It is possible to care for animals 
with less labor and time where all are brought together 
under one roof than it is wliere they are scattered through 
many buildings and Figs. 164, 168, 169, lYO and 171 rep- 
resent a consolidated type of barn with composite func- 
tions, where all of the stock are brought together under one 
roof. 







Fl(i. ItiV). — Coiisolidalcd 1 vpc of l>;irii showini;- (trivcw:! v t" tirst and second 

tlour. 

Economy in labor is of much greiatci' moment than 
economy in material because the material simply repre- 
sents money invested in this case while the (wtra labor re- 
quired is a continual expense^ of a high order. 



454. Distribution of Animals in Stables. — The ge-neral 
arrangement of animals in stables must vaiy in detail in 
almost endless variety, and individual circumstances must 
determine just what is Ixist. Three types of arrangement 
for cows are illustrated in cross-section in Figs. 150 to 159 
undei' the chapter on ventilation, and Fie. 162 rcTDresents 
two convenient groupings for horses. While Fig. 170 
shows one ])lan of division and arrangement of space in a 
cvlindrieal barn. 



373 




Fig. 171.— Showiiif; l-jss r-onsolidated typo of barn witli silo partly out side 

:3 



374 

A combined cow and horse barn with silo outside has 
the arrangement shown in Fig. 172 and permits the work 
being easily done. 

455. Avoiding the Use of Posts. — In cow stables having a 
second story it will often be potr^sible tO' c^irry the floor 
npon the uprights used to fonn the stalls or ties for the 
cows and in this wa.v save lundver bv making the same 




^^^ 



nnrsi ciose 



\ 



rlOf>S£ STABLC 



rr\ rr\ r\\ 



feCrO ALL£ 



B\0* SrjILLS 




■^ 






rerco alle^ 








5 














i; 




A 


i. 
















A 








CLEANING ALLCr 


\ 




MANURC onoP I* 1 








1 






















MAN&rR 




2< 


-J 






rcco AiiCr U 


■ 










MANGER 


















\ 
1 




1 






MANUfIC: OflOP It 1 


„ 



CLCAf^trve ALL£Y 



Fi<i. 172.— I'laii of comhiiUMl cow nnd horse barn with sUo outside. 

pieces render doiddc duty, and at the same time avoid the 
inconvenience of the posts and save the space they would 
oc-cupy. This plan is illustiated in ttlie various figures 
sliowinc: methdds of ventilation. 



STABLE FLOORS. 



456. Essential Features. — The essential features of a 
good stable lloor are: (1) Imperviousness to water and 



3 



i o 



iiriTio. (2) A surface siifiiciciitlv even to be readily and 
thorouiihly cleaned with a small amount of labor. (3) A 
dnrability approximating that of the building itself. (4) 




Fii:. 17:1. — Ki'cl;iii;;iilai- h.Mi. slmwiii;; (Irivcw:! vs to second aiHl third floors. 

A leasiinably low first cost. There are 'two materials 
which have been used in the construction of stable floors 
"which fulfill ihe-e i('(|uiiements; they are concretes made 
eitlier with Portland ccuicul i>r as])halt. The asphalt is 
supi'iinr t(t rlic Pdithind c(»ucr('t( in beiui>- a poorer con- 
ductor of hear wliilc tlic ccnicnt has the advau'tage of less 

fil-st C<!>St. 



457. Cold and Warm Floors. — It is urged against the con- 
crete as couipauMl with wood Hoors that they are cold. The 
meaning is that they aie Ix-ttcr coiKhu-tors of heat and so 
sei've to carry the heat away from 'the body of the animal 
raj)i(lly. It is true that they do c(mvey heat fa.ster than 
wood and when usimI in cohl (diniates without bedding are 
worse than wood from this stand])oiMt. They are not as 
])ad in rliis i-e^peet, however, as many imagiire. In the first 
])\<\i-i- the stable ought not to fall Ixdow 40 F., and when 



376 



this is tvwo the floor will only have this temperature and 
will not lead to inconvenience if other conditions are righ't. 
In the second place no animal should be required to lie 




174. i;.'cl!iii-ul-ii- 



I I'll w i I li (!'■'' 
US I'i 



t<i lirst .-inil tliinl Wnov- 



evein ujxm a naked win id floor and when ])lenty of l)edding 
is provided the cement iloor is not too cold for warm stables 
kept clean. 



458. The Use of Bedding. — ]STo farmer who is attempting 
to maintain the fcrtibty of his land at the standard of best 
yield can attortl to use no bedding- or ( vcn a scanty su])ply. 
He can better aflord to overfeed with hay so tliat the h^ast 
nutritious portions are rejected and use this for bedding, 
than go without, because the extra amount of manure made 
and the greater conifoit and clertnlines.s ni his animals will 
pay a gocwl n turn for it. The waste rougluigCi of the farm, 
when used as bedding and mixed with the manure, in- 
creases the value of both because it increases the total 
quantity of manure so nnicli that tbe flidds i-an be dresstMl 
more frequently, thus liobb'ng lb(^ hnmns content higher 



377 

a.n(l tlio mil in Ix-ttor tilth, l)otli essential coiHlitioiis for 
larg^e yickk The liability of aiiiiiuils to kiek the bedding 
off fi'oiii the; tiiKii- is net a suHieieiit i-easoii against cement 
flooi-s. Jt is oidy wlien too little bedding is nsed or it has 
not 'the right texture that the tloor is left seriously exposed. 

459. All Wood Floors. — These floors are generally laid in 
one of two ways, either close upon the gronnd, nailed to 
stringei'^; beclded in \]n- earth; or else niimi joists with an 
air space between the floor and 'ihe earth. When laid in 
either of these ways tlicy are certain to wear ont throngli 
the trani])ing of the animals and the use of the tools in 
cleaning the stables, but if conditions are favorable so that 
rotting does not occur they may last as long as 6 to 12 
years. 

It is oftener tnu that wood floin's give out from decay 
before they do from wear. AVhere the floor is kept con- 
tinually satui-ated Avith moisture it will not decay; and 
when ke])t continually di'v it gives out only through wear, 
but when it contains the right amount of moisture the 
growth of moulds, causing the decay, takes place. 

A\'h(^n the floor is bedded in a close textured clay soil, 
where the subsoil is close and all the time saturated with 
water, decay will go on very slowly; but Mdiere the soil is 
dry and open, and especially if this is the character of the 
subsoil, decay may destroy the floor in 3 to 5 years. So, 
too, Avhere the floors are laid upon joists on the ground and 
a dead air space left beneath, decay is certain to occur in 
3 to 5 yeai-s, but if the joists are so arranged that there is 
free circulation of air beneath, destmction from decay is 
not likely to occur. 

460. Making Wood Floors Water Tight. — Wood floors are 
made so as to pre\'ent M'ater from running through them 
by using more than one layer with some waterproof com- 
position between them. For heavy Hoors nuitched plank 
are laid and coated witli a laver of coal tar roofing; com- 



378 



])()sili(iii ,'111(1 llicii upon this ;i sccdiid hivcr dl" |)liMik is Ijiid, 
])jiiiiriiii;' 'tlici jiiiiits willi I lie siiinc comixtsil ion hclofc 
<lr:i\viiii;- llii'iii Inoct licr. Lilililcr lloors iiic iiintlc in I lie 
SilliK^ w;iv, usiiii;- |(>i|oiic(| :iii(| oi'(I(i\(mI llnoriliu-. 

461. Stone Floors. 'rii(.r(Mi,i;iil,v diirjiMc tloors lor cow 
.'111(1 lioi'sc sl.'ihlcs ;ii(" iii.'kIc 1>v hcildiiii; ill id;iv rounded 
coMdc sloiK", I or .") in(di('.-> in di;iiii('t ii , niid iisiiii; iipmi this 
:in jihniidiincc of licddini;-. 'I'lic iiiicNcii siii fjicc holds |,h(^ 
l)('i(hlini;- so well 'I hii.l I he :iiiiiii;ils jirc I'nirlv com forinhh' 
iliid neither wc:ir lun- (h'c;iv will d( -;lrov lliem. Idle inost, 
sefions ol)jecl loll lies in I he dilhi'iill v in iii;iinl;iiniiiii' (de;in- 
liness. 

Where a i^ood onttci- is nnide ix'hiiid the cows mid a row 
of" ciil sitone 10 *>v I:.' inches wide are set I'or I he hind t"eet. 
to stand npoii a (hiialde and (|iiili' satisfactoiN' thior is se- 
cured. 



462. Macadam Stable Floors. A Ihior i,i.>re i'\'eii in sur- 
lace than (461) cnn he made out ol" cartd'iilly constrncted 
niacadam work, siudi as is used in makiiia,' stone ro^ads, 
i^ivin^- it, a thickness n[' 't or (i inches. \\'li(>re this is used 
th('i'(v shonhl he pidvidi'd cement jj,ntters and maiii^'ers as 
re|)resente(I in \'\iX. 1 T.'>. 




Vut. ITfi. Shows iiM'llind ,il' iiKikiim :i inM.'a<I.MU sliililc llnoc willi ci'iiu'lil 
m.-i imi'i's ;i ml Linl I cfs. 

I'xdore layiiii;' smdi a thtor the ground sliouhl hv shaped 
and iiiaih' tlioroiii;lily hard l»y t rainpiiiu' or lainminf:,'. The 
ci'iished stone should l»e |)nl on in two layers, 'I liorouii,iily 
cinnpact iiii;- the liist layer and lilliiiL;,' tliv \dids with scrcM'ii- 



iii_i;s l)('f(»r() tlio surface layci' is made. Iinlccd the met hod 
sliould he the same as ilrat followed in iiiakiiijj,' a ^ood st.oiio 
road. 

463. Macadam Surface for Barnyard. Tlie |)aviii^' or 
flooring" the hanivard wilh iiiacadaiii siiirncc is |)'('rha|)S tlu; 
best sol lit ion of the dill ic II It proMciii of iiwiiiitainiiit!,' a, liard 
dry yard. ()ii accdiint of the piiddlini;- (d' the soil hy 'IIh; 
trauipiiif;' of f( ct, surface draiiia<;(' is all thar can be- ado|)'t<Hl 
and hence even win n the yard has hrcii niacadaini/ed it, is 
lieccspary to scra|)e the iniinnre iiih^ |iiles so that the water 
mav flow av\av. 



COXS'I'IMC'I'IOX" OF OKiMKN'l' I'l.OOlfS A.\M) WALK'S. 

464. Kinds of Cement. — TJiere are two classes of coiuont 
oji the. market, ( 'oiiimoii jiikI Poi'tlaiid. Of t he: coiiimoii 
cements in the I'liited Stales fjimiiiai- hi.-iiids are Akron, 
Louisville and M il\\aiik( e. 'I'lny are suitable for laying' 
walls beloAv i;roiiiid and plasteiinu cistcins but will not 
answer for stable, ('(lla r or cK anieiv lloois, iioi- for walk-, 
because they <lo not make a hard eiioiii;li sloiie. 

For walks and Moors -dnie brand (d I'oilland eemeiit. 
sliould ])ii used. These ai'e American, JMi^iish or (icrinan 
accordin<i' to the c<)untry in wliicdi they are mannfactured. 
Amei'ican hiands are N'idcaiiile, Alpha, Atlas ami Wol- 
verine. 

465. Cement Concrete. -Tluf makinf^' of cement concrete 
is ill efl'ect the production of artificial stoii" hy hindiiii;' to- 
^■itlier )>ieres of rock and -and with i'oitlami eeinent. 'I'Ik; 
cement is iton expensi\'e to he nse(| hy itself for ordiiiarv 
work and the makini;' (d cenieii' concrete aims to |)rodiice 
the lar^-est hulk of stronii' lock with the ii-e of the least ]H)S- 
sib](< amount. <if the iiioi"e co,stly ceinent. This is secure/d 
when only so miicji space is left between the materials 
bound together as will lea\'e room for the cement to form 



;;,so 

.•I I III II l;i vcr I II (w I ell I lie fncc^s df t| Ire rr':ii;iiiciils to he joiiicd 
Ic.iicllicr. 

46G. Materials for Concrete Floors. 'I'lic in.ilcrinls used 
liH- ('(Miiciil walks ;iii(l lldors sIkhiM lie (1) :is l;ii'p\ clean 
I riiUiiicnls (p| linrd rock ;isc;iii Iti' rc;iililv mixed ;iiid worked 
ildollie loniis ,iiid I liickiiess el' l;i vcr desi !■( d ; ( "_' ) :i liner 
liTildc (d ci'iislicd rock or coni'sc clenii i;r;i\'el wincli will 
rciidilv |i;ick iiilo llic voids lietwecn the l;ii-i;t r rrn^iiicnls ; 
(''>) :i clciiii, Co; I rse, slmi'p s;ind le li II I lie |>()res jtcl ween I li(> 
I r:ii;inciils ol i^rnvcl or line scrccniniis; ( I) cnonuii i'oii 
land ccincnl lo lill llie s|i,ice liclwcen llie siind and Itind llu^ 
whole loi^'clhcr; ( ."> ) :ind liiinllv. \\:iler enoni!,ii lo wet all 
siirlaccs, lill the |iore spncc o|' the ceiiu'iit ;iiid nnike lli(> 
liloll;li- pl.'isl ic. 

467. Presence of Earth, Loam or Dnst. It is (d' I lie great- 
est. ini|)oi'l;ince lh;i! ;dl of I he ni;iteri;ils \\sv^\ he pcrtectly 
tdeaii ;iiid I I'cc li'oiu diil or other line i;r;iined ni;iteri;d 
lia\'inu- I he l<"\l lire vil' 'I he ccnicnl ilsclf. 1 I' ;i line dnst is 
prrscMl in the roi'k, i;r:i\('l oi' s;ind il will lend lo form a 
l;iv( r over the sni'liiees ol' the I r;iij;iuenls wliieli prexcnts 
'the e( ineiil lidiii eondii^ in eonl;iet with I he jiieees whicdi 
ar(* to lie eeiiieiitetl toi^elher ;ind ;i we:ik eoiierele rcisnlts. 
The Iniidiiinenhil is |o h;i\(' iioihiiij^' lull li;ird roek t r;iii'- 
nieiits hiroc ciionuli lo lie eeiiu irleil tou'elher ;iiid inMhing 
line preseiil luil t he eeniriit iiii;- iii:ileri;il itself. 

In I he eoiierete |i;i\ eiiienls used on t he si| reels el London, 
;iiid which li;i\i' :i iiincli longer life tli;in the Itest ])aving 
blocks, t;re;i>t tMiv is taken lo wash onl (\{' the cnished 
iiraiii'lc ;iiid its scrceninus ;dl dnsi |i;ii'li(des before \isini2; 
tlieiii, idlhonuh the dnst m;iv he iVoiii ihcL'rnnitc itself. 

468. Wettiuj;- the Crushed Rock Before Use. There are 
I wo iin|ioit;int reasons wliv cnished vovk [H' coarse screened 
li'raNcI, lo he nsed as tlu> hodv of concr(>t(\ should be wet ho- 
fi>re niixinii' with the cement. Thesi* are (1) to dis|)la('0 
as much adherinu' air as |tossible, and ( iM so as not to draw 



;{Hi 

(Hit (Vmii llic (•(•iiiciit llii' \\;it(i' ii((''lc(l Id iii:i!iil:iin ils 
|)liist icil \ ;ili(l In ;is-isl ill I I K • S( 'I 1 i 111;'. 

If llic (•(i;ii'-i' iii;il('ii;i Is iiic mixed wrlli llic (•ciiiciil ilrv 
;i l;iri;(' niiKiiiiil <il ;iir will In' set free :iihI ciitiiii^lcd in llif 
(•(Hicrctc, W'liicli will |iii'\('iil ;ill s|>;ic(s Itciiii;' lillcd, Iml llic 
»'lli( r ilillicilltv (•(lines iVdiil llie ;iil' pi e\'eni| i lli;- the cenielil. 
lloiii ;i(llieriiiu' lo llie ■^iii'hices. S( i slrdii^'iv (|(ies ;iir ;i(lliere 
!<► cdiii'se siiiid I lull il iiiii-l I le Ik n l( d sniiiei I iiiic ii iider wilier 
li( lore il is ;il I renid\ cd. 

469. Ratio of Ingredients for Concrete. 'I'lie .iinoiiiils of 
(';icli iiiiiredieni ic(|iiii'e(| Id iii:ilse :i solid cdiieicle willi :ill 
spiices lilled depi'iids ii|idii llie |idfe) spiice in llie di ll'eircilil 
iii;ileii;il-. 'i"i';i ill w' i lie ;issiiiiies lli:il. I'di' e;icli i iiij rc( I ieirl llie 
\'<i'ids iire iieiii" eiidiiiili Id' ■'»() per cent . sd I li:il ;is ;i s;i fe work 
iii<i' lijisis I his shdiild he hikeii. 

'I'd lii;il<( ;i cilliic v.'ird (d' cdiicrelc il woilld he iiecess;irv 
id use, (III 'I'm III w iiie's hiisis, 

('ni.sJKMJ i<(cl>. ( f lav el or scHMMiinnH, Coiirsc hiiikI. ('iiiiniil. 

•^7cii n. i:!ri<-M n. (i '.iricu. n. :i ri.'i cu, n 

This rill id jdi- pdi'e splice iscerhiiiilv hir^cr ih.'iii is likelv 
Id dcciir iiiid Idr hiriii piirpdses il will he s;ile eiidiii^h Id 
f;ikei I he i;il idS id' 

("rusllcd .Kick, ( J|•MV(^I in- MTIM^IlillKS. .Sllllll ('llnilll 

27cii.ri. i'ioii CM. II. ri-'ihi cii n. z.i'.i'.icii. n. 

'rii(s(' lii;iircs iissuiiie llie pdrc' ,s|iiic(' nl I hci I'ocds to \)\' 47 
])(•!• cciil., (if llic <:,rii\('l 11 per c(Mit. 5111(1 of tlio Hiuid .']8 per 
<^('iil. 

470. Ratio of Ingredients for Finishing. Wlicic ^ood 

pljl.slcrili^' s;iiid is used I'di- iii;ikiii^; IIk lliiisliiii<;- siirlMce llic 
]rdi"ci sp;icc Id he Idled will lie iilidiil, ."..'"i per ceiil. :iiid lliis 
Wdllld rcipiirc ;i little nioic tli:ili dlie dl ceinellt tdilhrccidl 
sjiiid, iiiid unless there is sonic ^I'Jivcl or scrcciiiir^s to use 
with tlic sjiiid id will he siifcr to iiuikc llici i'iiciii^' 2 of sjiiid 
lo I dl ccinciil. 



382 



471. Thickness of Floor — For most stables wlun-e the 
ground has l>p<m well tinned and sluqx'd a thickness of 4 
inches of coiicrete and oiie-half inch ^of facing will bo 
fenongh ; for house cellars and for the bottoms of silos 3 
inches of concrete and onc^-fonrth inch of facing will do. 
For cremneries and milk rooms the concrete Ik tter be 4 
inches and the facing a full halt inch, made I'iclicr in ct>- 
ment, in th'e ratio of one to one. 

472. Making the Concrete. — The cement, sand and gravel 

are put together drv on a mi.\in<2,' board and thoi'oughly 
worked over, then enough water added to make a stitt' paste. 
The right amount of crushed rock is thoroughly drenched 
with water and the whole mixed bv shoveling nntil the 
rock is thoroughly incor]iorated with the cement. 

473. Laying the Concrete. — The floor of the stable should 
first be given the ]iro]>er form and very thoi'onghly tamped 
so that no settling shall occur after the floor is laid. The 
concrete slnmld be laid in blocks foiir or five feet square, 
bnildinc,- alternate blocks first, Fig. 170, so as to give time 




for setting and prevent a strong union of the blocks. If 
the floor is not laid in this mannei- shrinkage cracks will 
occur. The concrete should be nnide oidv as fast as used 



183 



and sliould 1.;' tlioi-ouiiiily raiiiiii('(l uulil the tine ('('incut 
shows as a layer on the surfact'i. Af'k'r staiidiui; a slujrt 
time, but hefon^ tiie concrete has set, tin finishiuo- surface 
should he ajjplied and thoroug'hlj trowelcHl until it is even 
and smooth. Fig. 177 is a cross section of floor and 
manners. 




Fl<i. 177. — Sljdw 



■K'l'ridii (if i-fiiicnt stalili 
unrO'i-s. 



HiKir with iiiniiiicrs and 



For a cellar or creamery flo(jr, where k is desired to have 
a fine smooth surface, easily cleaned, after troweling, it 
may be wet with a whitewash brush and s(nue ])ure dry ce- 
ment siu'inkled over, which is troweled until it is hard, 
smooth and glo.-sy. 

When the second series of blocks in a given tier is made 
and the surface finished it is necessary to cut thnmgh the 
finishing layer exactly above the joint in the concrete, to 
prevent cracking, and then neatly round the joint. 



474. Cost of Materials for Cement Floor. — Taking mater- 
ials at the j)rices given and the concrete -i inches thick, 
made in the proportions of (469) the cost per 100 square 
feet of fl(5or, and the amount of materials will be as given 
in the table below : 

The floor made (d" wood 2 inclies thick, laid upon 2x<!'s, 
10 inches from center to center, would cost $4.12 ov $4.1)5 
])er 100 s(|uare feet when the price is $15 or $18 i)er thou- 
sand. Til is makes tlie concrete 91) cents per 100 square 
feet more than the lumber, comparing the lowest prices in 
each case, and $1.72 more, comparing the higher prices. 



384 



Material required for 100 s({uare feet of concrete floor 4 inches 
thick with one-half inch of facing/. 



Material. 


Amount. 


Cost per 100 sq 


ft. 




1.23 cu. .yds 

J'-i cu. yds. . — 
3.76 cwt 


$ .80 percu yd. 
.50 per cu. yd. 
1.00 per cwt. 

Total 

1 00 per cu. yd. 
.7.'i per cu. yd. 
1.30 per cwt. 


$ .9S4 




.365 




3.760 




1.23 cu. yds 

.73 cu. yds 

3.76 cwt 


5.109 
1.23 


Sand and gravel 


.55 

4.89 


Total. . . 




$6.67 











Where crushed rock cannot be had, but coarse gravel and 
plastering sand are available, a good floor can be made, but 
more cement must be nsed, nsnallv 4 of sand and gravel to 
1 of coment. 



TIES FOR CATTLE. 

The methods of tving cattle must vary widely witli the 
taste and objecitis of the owner. The esseintial objects to be 
secured are: (1) comfort for the animals. This is neces- 
sary whetheT the main object is milk, breeding or beef ; (2) 
cleanliness, and (3) economy of time in tying and of space. 




Fig. 1/8. — Wilder swiugintj stanchion. 




Fig. 17y. bcoit self-clt)siug swinging 
stanchion. 



475. The Stanchion. — There is no tie for cows, if we ex- 
cept the phiiu lialtcr or rope, which lias been so nnivei"sally 



385 



used ;i- one nt tlic Inniis of st;i iicliidiis rcpi'csciitcil in Fii;s. 
178, 175* and IS!). It is tlio ,siin])l(',st, clicajx'st and most ex- 
iveditioiis tic invented iind the s\vin_ij,inii- forms wliicli ])('V- 
init the yoke to Inni and to mo\c a lilllc \n\ck and foi'th 
])rovide a reasonable amoniit ot conifoii; and where the 
\vi(hh of thci platform is aihipti'd to the si/e of the aiunial 
they seenre as hiuli a (h'iiree of v-leanliness as is |)i';u'ti('alih'. 





Fig. ISO. -Tliorp stall. 



IFiG. 181. -Drown -tall. 



476. Adjustable Stalls. — The four stalls represented in 
rii>s. ISO, 181, 182, and 183 are designed to give the cows 
the maxinmm amount of freedom of head movement but to 
force tliem to stand close enongh to the gutter to preveu't 
the platform being soih'(l. The manger or the head of the 
Htall is made a<ljustal)le so as to ciowd the cow hack against 
the chain in the reai- \vhi(di conhnes hei'. J^ractically there 
is no form ni' tie wlii(di can })revent the cow from soiling 
the platform n|)on which she stands on acconut of the un- 
changahle habit of shoi-tening the bo(|y by humping the 
l)a(d< when the ex'acnatioiis occui". 




Fig. 182. -Roberts stall. 



Fig. 1s:i -Hi.lvvell stall. 



386 



Tlic t\v(i stalls, Fiii's. INT), 18(i, have bt'cii d(,'sii>ii(.:'d to se- 
cure clcauliiuss ill spite of this habit. Tn the !N^ewton tie 
it is cxjx'c'tcd that wliilc the cow is stand inc; the yoke to 
wliich slie is tied ^vill force her hack siiffici(Mdly to prevent 
the (lillicully. In ])racticc. liowcvcr, tlicre is necessarily SO 





Fi(i. 18J.-Halcrr tie. 



Fig. 18.'). — Newton ti(*, 



niucli frccdiiiii al the lu'ck tlial 'tlic dhjcct is luit scu'urcd. 
'I'lic ''.Mixicl I ic" |)i'()\i(lcs a har on tlic lloor, just in front of 
whcr(^ tlu'i cow's feet are forced to lie while standinii,- and 
fVedini;', and Avhich is so nnich of an ohstruction that in 
order to lie in ('(inifoit she steps forward enouiili to lie on 
t Ik (dean heddinii-. 





Fifi. 186. Kiii»pv> tie 



Fic. 187.-"Model tie. 



387 



477. Movable Halter Ties.— Anothrr class of tics repre- 
sented in Fii;s. IS I, ISS, ntteni])! to eoiititie tlie cow in 
movenieiitw forward aiul hackwaid hy iisiui;' a short cliaiii 
which slides at the other end in siudi a iiiaiinei' as to per- 
mit freedoiu of iiioition up and <hi\vn. 




Fig. isa.- Cliaiii tie. 



Fid. 189. KiKid .stanchion. 



478. Tight Side Partitions. — Tliere is an eifort among 
some feeders !(► prevent the animal frcun nio\'in<i' sick'wise 
so as to interfere; with the neii^hhor, either by stepping 
n])ontlie feet or teats of the cow lying down or of taking the 
f(M>(l from the mangei*. Wliei'c sn(di ])rovisions arc insisted 
ni)oii it shonhl he kcjit in mind that anything whicdi tends 
to enchise the eow, especially her head, in a tiglut box tends 
in a high degree to defeat the ])nr])oses of good ventilation 
by confining the air once bicathed about the ainmal, hence 
such arrangements should be shittecl oi' else (,pen at the level 
of the flo'Oi'. 

So, to(N \vlier(ver box stalls are used thewe should be 
slatted or o|)en at the bottom and not "boxes" as they too 
often are. 



479. Tying for Feeding Only. — For calves, yonng cattle 
and feeding steoii*s 'there is ])erha])s no mode of confining 
the animals in the stable so good as to- give them complete 
freedom except at the time of feeding, using ]denty of bed- 
ding on a cemenil^ floor \vhi(di is (deancd as often as needful. 



388 

111 siicli cases the staueliioii tie is the best as eA'erythiug" is 
then reduced to the simplest conditions. 

480. Mangers. — One of the simplest mangers for feeding 
cows is represented in Fig. 177, and when made of cement 
as represented in the cut it is the best for feeding, cleaning 
and watering, where large nnmbers of animals are to bo 
handled with the greatest economv. The manger should 
have an inside Avidth of at least 2 feet, a depth of S inches 
and should have its bottom o or 4 inches abuve the plat- 
form upon which the coavs ^itaiid. 

481. The Manure Drop. — This should have a width for 

adult cows not less than 18 inches and not more than 20 
inches. Its depth next to the animals may be 8 inches and 
on the rear side C inches. These dimensions give ample 
capacity to prevent the walk behind from being soiled and 
make it easily cleaned. 

On some accounts a depth of <> inches next to the cows 
and 6 inches in the rear is best; and where a wagon is 
driven behind itlie animals to clean the stable a depth her 
hind of onlv 1 inches cives k\ss hiuht to lift the manure. 



PKOVISIONS FOR WATEEII^G. 

Where there is a well of ample capacity, and 30 or more 
cows are kept, the best arrangement, everything considered 
is to pump 'the water from the well at the time it is needed. 
This plan provides water that is both fresh and natural 
temperature, and does away ^vith expensive storage tanks. 
In case the power is pumping waiter faster than is needed 
it is a simple matter to ju'ovide an overflow, returning the 
water to the well. 

482. Watering in the Barn. — In climates having severe 
winters it. is best, if practicable, to wat.er the animals in 
the barn, and where a good fresh running stream can be 



389 



inaintiiiiicd the idciil \v;iv is to Iinxc tlic water before the 
cows all the time so tlia'f it can Ix- taken when desired. 

It. is not (h'siial)h' to keep watei- standing' before the oows 
continuously as it is certain to become foul; but it may be 
maintained dm iiiii- the uveatf r part of the day if the drink- 
ing- basins or trouiihs arc em])tie(l chan each evening'. 



483. Methods of Watering in the Stable. — We have seen 
but 'two r('asonal)ly satisfactory methods of watering a large 
nnnd)er of catth' in the stabU', and these are either to clean 
the maiiiicr ami luu the watei' into 'that or else to have a 
special liiiiii' wateiiiiii' tiough us'.'d for that alone. 




Fin. ]i)0.-Siini)l 



incut for wjitcriiij;- <•' 



in stal)le. 



The sim])l(st airangement of s])ecial trough is repre- 
sented in Fig. 100, and extends the full length of the stable, 
the wat( r cduiin^ to it from above so tliat the supply pipe 
is entirely above gidund where it can be gotten at and can 
be emptied at once after using. The trough is covered its 
entire length with a hinged lid, but in front of each cow the 
lid is cut so the cow can raise a section with her nose when 
driidsing, letting it fall when .she is through. 

484. Storing: Water in Tanks.— Where there Is a basement 
barn the heM. ai'raiigement for a storage water tank is a 
24 



390 



cement lined cistern benea.tk the surface in the hill above 
■the barn. {Such a cistern is Ictss expensive, is a pennanent 
improvement and will keep the water warm and clean. 

We have seen cases where a satisfactory cement lined 
cistern is built entirely abo\'e ground and then covered in 
by grading- a mound of caith about and o^'er it sufficient to 
make it frost proof. Such a cistern should be provided 
with a man-hole so that it may l)e entered if necessary. 

485. Watering Trough. — Where stock is watered in the 
yard a good arrangemeu't for \\'inter, where the ground is 
porous, is represented in Fig. 101. The tank is a galvan- 
ized cylinder 3 or more feet in diameter and 5 feet deep 
which stands in a dry well 15 or more feet deep and so ar- 
ranged that the warm air from the bottom of the well all 
the time surrounds the tank and keeps it from freezing. 
Water may be pumped into this direct or it may be sup- 
plied from the bank cistern. When it is necessary to 
em]:>ty the tank the plug can be removed and the w^ater al- 
lowed to drain into the dry well. 




Fig. 191.— Representing a sti>r:i.ue rescrvnir .ind drinking tant; arranged to 
avoid freezing. 

It is of course important to provide a warm jacket about 
the tank and cover, as represented, so as to assist in keeping 
the water warm. 



301 



AKRANGEMENTS FOR UA^LOADIiN'G HAY. 

486. Unloading Direct from Wagon. — Where the hay is 

not to be lifT('(l and can Itc rolled directly from the wagon 
with the fork into the bay, there is no simpler and more ex- 
peditions way ; and where the load can be driven to the top 
of the Larn, as re]>reserited in Figs. 168, 171 and 173, there 
is little need of other mechanical arrangements. 




Fig. 192.— Curved track aud hay carrier for use in cylindiifal baiu 

487. Unloading Hay in Cylindrical Barns. — Where the 
cylindrical type of barn is used there arc two methods of 
distributing the hay; (1) that represented in Fig. 192, 
where an ordinary hay carrier is moved over a curved track 
and (2) that re])resented in Fig. 193, where an ordinary 
hay carrier delivers the hay upon a central inclined plat- 
form, which is turned about by the operator in the bay so 
as to deliver the hay at any desired point. 

488. Tilting Hay Distributor. — It is possible to take ad- 
Tantage of the princijde illustrated in Fig. 193 for distrib- 



392 




Fig. 153.— Ordinary hay carrier and revolvinfr platform for distributing 
Iiay in (\\iindrieal barn. 




Fig. Iit4.— Kepreseuting a movable, tilting platform for distributing hay 
in rectangular l)arn. 



393 

iiting hay in ordinary rectanoular barns, Avliose timbers are 
not in the way. Fig. lU-t represents a tilting platform, 
which rocks upon two bars carried bv four cables secured 
to pulleys which roll along tracks or cables secured to 
rafters, as shown in the cut. With this arrangement hay 
may be drop])ed at either side or in the center of the bay, 
as desired. 



;;i>i 



('ii.\rTi<:ij XIX. 

CONSTRUCTION OF SILOS. 

489. Conditions Essential (or Preserving Silage. Tho 

(tiilv ('oiidil ions IK rcssii I'v l<n' |»r('S('r\'iiiii i^ddd corn and 
,('lo\'('r silii^c, ;if(' close pnckiiii^ in :iii ;iir li<;iit, st I'licturo 
wlicii I lie iiiiilcriiils li:i\(' rc:iclic<l I lie rii;!il slai2,'(> of inatiir- 
ily. W'liatcN'cr nicaiis ni:iv lie :i(lo|tte(l lo e\cln<le iiir from 
lliese iiiiilcriiils will presei've I hem ;is sil;ii;'e. If nil- caiL 
liiul necess lo il s|Miiliiii; will he iiie\ iliihle nud llie rjilc and 
exlcnl will he i;i'e;iler I lie more reiidilv :iir e;in i;;iiii aecioss. 

490. Depth of Silage. The dei)lli (d' sila,i>o HJionld bo 
ni;ide as i^rciil :is |tr;iel ienhle ( \) heciinse in lliis way tllG 
hu'iicst nniouiil (d feed |»erenhie fool m:iv he slored. (2) 
There is less loss r(lali\'ely ;d I he siiid'iice. (-'!) The si ronj; 
hilcnd |»i'essnre forces llie silage :i,i;ainst llui walls so 
tdoselv lli:il less ;iir cnlers :ind hence lliere is less loss. 

491. Silo Walls Must be Rigid and Strong.^ The oidward 
pressure (d' cnl corn sihii^c when selllin«;', nt the iinio of 
lillinti'. increases will; (lie deplli id llie r:ile (d" 11 lbs. per 
K(piai{^ I'eel for eiudi fool (d' deplli. A I ;i deplli (d 10 ftH'ifc 
(Jie laleral pressure is 1 10 Ihs. per s(pi;ire fool, al L*0 f(>et it 
is ^20 Ills, ami :il .".O feel ;'>;;0 Ihs. 

ilcciin-i' (d' ihis i;re;il picssiirv silo \\;ills iiiiisl lie mado 
v'ci'V si roiiii,' when llie\' li;i\(' :i deplli (d "_'0 or nun'c led. It- 
is (lillicnll lo in.'ike deep !'ecl;iiijj,iil:i r silos whose wnlls will 
M<»l spread as i-epreseidcd in V\'j;. ll^T), and wlicre (bis takes 
place the Willis iire i-rowded iiwiiy from (lie sihiiid so iniich 
(hill iiir ciiii circiil.'ile up :iiid down nexl lo llie Wiills timl 
(his rrsiills in lie;i\ \ losses. 



,".'>r. 



Ill t'ii'ciihii' silos llic prcissiirr is siisliiiiKMl hy iflic Icnsilci 
stnMJ^'di of I. lie iii;il(ii:ils in I lie walls, wliicli i;i\'cK lliciii Ijic, 
jiTCJitcsl [xissiUlc ii(l\:iiil:i^('i. 




m. 




I'lt; 1:1.",. llhisl i:il ill;; liipw Ihc liiil;;lii;^ iiT reef 1 n„iil 11 wooil silo Wiills 
illlipws iiii' Id (■(line down llic siilr'^ liclwccii I lie Willis :ill<l Ihc sIlilKC, 
<'inisiii^' il 111 s|i(ill. 'I'lir ,'i iiiiiuiil III' s|ir(Miliri«- is i'Xiikk»'1''iI<''I i" "'<" 
lljjurc I'm' clr.ii-iu'ss of illusl ni I inn, liiil II is nnni' Ihc less rciil. 



492. Silo Placed Deeply in the Ground. — In most cases it 

i:s best, to allow IIk^ silo to extend jis (Iccply into the <i,-roiin(l 
as convenience ill icnioviiifi' the materials will |K'nni(. 'I'lii.-i 
can always he as iiiiieh as .'J feet helow the feediiio- floor and 
ill the ease of hank hariis wlicn; tin; silo can he |)laccd in tho 



;^06 



liill ;i (Icplli 111" 11 or iiKiic feet cnii (>nsilv he scciuhmI. 
PLaeiiig' llui silo dec]) saves t'l('\;itiii<;' I lie silage so liioji 
Avlu'ii lilliiiiiand a lai'uc |)(»rti(iii ol" it is hrlow tVost. 




Flc. l!i*i. -Slio\\iiii; !iii nil stone silo with roiiiciil roof ,iu<l opoi)ii\!,'s fov 
recdiiiu: doors; the licnv.v Mack dots 1. 1. 1 show \\ hero Iron rods may 
ho hcddi'd in the wall to proxcn' crackini; t'roni llio pressure of the 
sriajAi'. Method of const met inn' silo door ami door Jamh for stone 
sflo. K shows cross section of silo door, 1"'' sliows how the door 
Jamil is nnide to make it air tij;'hl. and how the door is licid In place 
with laK holts auainst a .uasket of rui>croid roolini;-. 



493. Protection Against Frost. — Tt is not iiocossary to 
build a. silo so as to he ciitifcly frost proof in cold (dimatt^s, 
but it will pay in hiiild tliciii rcasonaMy warm whcroi they 
ai'O to 1h' fed froiii diiriiiii' cold wcatlicr. The iVo'O/ing" of 
silage dtx's not injure it seriously but it is uct wcdl to fe(>id 
it wlicu frozen. If a siloi is not to bo o]>eiu^d until warm 
woathior no s]>oeial atteutiion need b(> oiven lo warinth. If 
a silo is 10 to II) foot in the ii'round and onlv iM) feet above 



897 

ground, tlic scttJiiii;' mu\ the early feeding' before s(>vere 
cold wealthier will usually have carried tlie surface of the 
silag'c so low that little iiiconN'cuiencc I'roin tr(tst will b(; 
experienced c \-en in stone silos. In all the Wdixlen silow, ex- 
cept the (luestional)le staves tv|)es, 'Hie const rucTioii neerled 
for streiiiith and to ke(q> the air fi'oni the sila,i;(; will usually 
be a ^snfi^cient pi-oteclion a<;ainst frost. 



OOA'STIlUfl'ITOX OF STONE SIT.OS. 

Whenever stone can he liad on the farm suitable for 
l)uildinii- pui])oses these may be u^^i'd in silo c(jnstniction, 
thus coTLvertin^- idh"; into active cai)i'tal. So far as the silo 
itself is concerned no bettn- oi' moi'c dui'able material can 
be used, an<l where it can be 10 to IM feet in the uround 
'the inconveinCncesS from freeziiii;' will be small, and the 
stone silo will be found one of the cIk apest of the thor- 
ouii'ldy *j,ood foiius. C}]-eat paiiLs should b(} taken in build- 
ing tli(^ walls to fill all sj)aces between stones solid wit.h 
smaller ones and inor'tai' and to liave them ,thoi-oughly 
b(^)nde(| in oi'dei- to secure- strenutli and prevent cfa(d\in,u'. 

494. Laying the Wall. — The jjortion of the silo wall 
wliicli is below around bettei" l)e about '2 feet thick and laid 
in one ot the (diea]) brands of cemen't lather tiian lime, tlx; 
cement iM^inji- desirabh? because lime mortar becomes hard 
so veiy slowly in heavy walls, esp<'cially behw ji'round. 
After the Avail is two feet above lii-onnd i^ood lime mortar 
may be iLsed, but in this case there; ought lo Ik- at hast two 
months for the wall to season and set before filling. The 
npper ])ortion of the silo wall need Tiot be heavier than 18 
inches, and if the size of stone ])ermit of it, the outer face 
of the wall may ])e drawn in gradually to a thickness of 12 
inches at the top. 

Too great care cannot be taken in making the part of the 
wall below and near the ground soIi<l, and es])ecially its 
outer face, so that it will he strong where tlu; greatest sitrain 



P,98 



will come. It is l)ost also to' diii' tlic i»it for the sil(» large 
(^iKi'Ugli so as to have j)leiiit_v vi room oiitsidc nf the fiiiislied 

wall to jxu-niit the earth 
tilled ill beliind to be very 
thorontrhly tamped, so as 
to act as a strong backing 
for the wall. This is 
nrged because a large per 
cent, of the stone founda- 
tions of wood silos have 
(•ra(*ked more or h"ss from 
tnie cause or another and 
these cracks lead to the 
spoiling of silage. 

Flat quarry rock, like 
limestone, will make the 
strongest silo wall, be- 
cause they bond much 
better than boulders do, 
and when built of lime- 
i stone they will not need 
to be reinforced much 
with iron rods. It will be 

Fm. 197-Shovvs tlie inetliod of jacketing a best CVCU in tllis CaSC, 
-stone silo to protect it asramst frost: the . . ' 

Iieuvy black squares are blocKs bedded into however, tO USC; tllC irOU 
tlie stooe wall to wliicli eriris or studs iiiav • t i i i 

be nailed to carry the siding. tie rotis Ix'tWCCll tllClOWer 

two doors. 




495. Plastering. —The inner face of the silo wall should 
be plastered with a thin coat of ricdi ceincnt not leaner than 
1 of cement to ll/> or l' of (dean ^^harp sand. If I he uiortar 
is not rich and troweled smooth, the acids of the silage will 
act upon it nnudi move rai)idly, dissolving out the lime and 
leaving it open and ])orous. 

It Avill usually b(^ pnident also to whitewash these linings 
every twO' or thrxH'i years, espcndally the lower portion wdicre 
the sihige is longest in c(Uitact with the cement, in order to 
proA'ent softening, using cciment to make the ^\•ilitewash. 



80 !> 



496. Doors. — Doors for filling and feeding should be ar- 
ranged as re])rcsented in A, Fig. 196, and if the lower one 
is long, cntting out a good deal of the wall, an iron rod 
shonld be bedded in the wall above it to prevent cracking 
between the doors. The rod shonld be of f inch ronnd iron 
l)ent to the curve of the circle and about 12 feet long. The 
two ends shonld be turned sliort at right angles, so as to 
anchor better in tli(' mortar. 

In deep stone silos, which rise more than 18 feet above 
•the surface of the ground, it Avill be safest to strengthen the 
wall betwe(^n tb(' two Idwci- doors with iron tie rods and, if 
such a. silo, is built of lioulders, it will be well to use rods 
enough to make a t'oiiii)letc line or hoop around the silo 
about two feet above the ground, as represented in Fig. 
198. 




Fia lOS.-SlM.wiiiK iiH^thod ut iHMldiHfi iron rods in stone '"'i'-k "'• con- 
;-ivt(- silo walls to incrensf. tlu- str(.ni.'lli. The li.-avy lines with ends 
bent represent the iron rods. 

The door jambs for the stone silo are best made of -lrx4'8 
framed together and set far enough apart to give a depth 
four inches less than the t.hickne^'w of the wall. This will 
allow mortar to be filled in between the 4x4's to make an 



400 

air-tig'lit joint. A (Much board inav he fitted around the 
outside of the inner side of the door jand)s to form the rab- 
bet for the daois, or the jambs may be made as rejiresented 
in Fig. 19G. There will be slight shoulders left in the 
round stone silo above and below the doors when these are 
made flat^ and these should be filled out with mortar when 
plastering, giving a long, gentle slope back to the wall. 

The door is beet made of two layers of 6-inch flooring, 
tongued and grooved, ciossing at right angles, nailed or 
screwed together, Avitli a layer of good acid- and water- 
proof paper between, as shown at E, Fig. 196. To make 
the door fit j)erfectlj air-tight there should be tacked to the 
face of the door jamb, all around, a wide strij) of thick roof 
paper or strips of old woan out rubber belting, and the door 
drawn u]) against this wirli tour ^A^^ ineli lag bolts })ro- 
vided with washers. 

If one prefers to do sO' the door may be made small 
enough so as to leave a half-inch s])ace between it and the 
jamb all around, and this space filled with puddled clay 
after the door is ]uit in ])lace. Either of these methods is 
better than to tack striji.-i of tar paper oA-er the joints. 



CONSTRUCTIOlSr OF BRICK SILOS. 

Very excellent silos may be made of l)rick, as repre- 
sented in Fig. 199, and where brick of a good quality can. 
be obtained at $4.25 to $7.00 per thousand a silo Avhich will 
last indefinitely may be made at a moderate cost. 

497. Foundation. — The foundation of the brick silo is 
beet made of stone, wherever these may be had, canwing 
the stone work u]) at least a foot above the gTound and be- 
ginning below frost line. The l)rick work will then be set 
with its inner face flush with the inner surface of the stone 
work. 

If the silo is to be carried 20 or more feet above the stone 
wall it will be desirable to bed a f-incli round iron hoop 



401 



into the n])pf r surface of 'the stone work in order to guard 
against eiaeking- tlu^ wall \>y the pn^v^nre of tli^ first tilling 
before the mortar has lia<l time to thorouiihlv season, which. 




Fi<;. 199.— Sliows an all-l)rick silo with Wiill 14 inches thick niiulc of three 
••ourscs of brick, the outer course beinjr set so as to form a 2-iuch 
(lead air space as liiaii up as the slioulder. 

does no't take phiee nntil after five or more months. The 
method of laying the sections of iron rod in the wall is rep- 
resented in Fiii'. 198. 



402 

498. Walls.— In cold climates it will be best to make the 
lower jioi'tion of the wall, up to within 10 feet of the top, 
with a 2-inch dead air space, nsing three courses of brick, 
thus making tlie wall 14 inchcB thick, for all the smaller 
and medium sized silos. If tlici silo is to exceed 24 feet 
inside diameter the lower third of the brick wall should 
be made of four courses of brick and 18 inches thick, 
the second third 14 inches thick, and the upper third 8 
inches, solid. The dead air space should be next to- the 
outside and this course of brick should be tied to the inner 
wall as frequently as necessary to make it stable. 

499. Strengthening the Walls. — The tendency of the 
pressure of tlie silage to crack the walls of round silos in- 
creases with the depth and with the diameter of the silo. 
The tendency of the silage tO' burst a silo 26 feet inside 
diameter is twice as great as in one 13 feet in diameter and 
the same depth, and this makes it necessary to strengthen 
the walls of th^ larger brick silos. In all brick silos there 
should be an iron tie rod bedded in the wall, in the manner 
illustrated in Fig. 198, between each of the lower doors to 
oompensate for the weakening caused by the doors; and in 
the larger silos these ties should extend entirely around the 
silo in the manner shown in Fig. 198. 

500. Wetting Brick. — It is very important in laying the 
brick for a silo wall that they should be wet and especially 
if the work is done in hot, dry weather. It this is not done 
the brick will so completely dry out the mortar that it can- 
not set properly and become strong. 

501. Making Walls Air Tight. — There are several ways 
in which this may be done, and some of these will be given 
in the revere© order of their effectiveness. 

1. After the wall is finished it may be simply given two 
coats of thick cement whitewash, and this re]>cated every 
two or three years as the acid of tlie silag'e: dissolves it away. 

2. The face of the brick wall mav be iiiven a good, rich 



403 

coat of cciiu'iit })lastor, oiic-fduitli to (iuc-lialt' an inch thick, 
and tlien this he k(>])'t whiti waslxyl so as to nculfali/.c: the 
acid and prevent it ficiii softening' the cement. 

8. Tlif^ wall, or at least the inner portion, may he laid in 
rich cement mortal', makini; the horizontal joints ahont one- 
fonrth of an incdi tliick and the A'crticai ones a half inch 
thick, takinii' gicat care to get all joints of the inner 'tier of 
biick thoionghly filled with mortar. This method will 
place 'the cement where it will not be as readily affected by 
the acids and fVost and does away with the necessity ol" 
plastering, care being taken to lay the brick smoothly and 
to point the pints carefully. Milwaukee cement will answer 
for this work. AVhitewashing the inner face of such a 
lining will be sufficient for smoothness aud tightness. 

4. The very best possible lining which could be made 
wo'uld b(^ secured by using the small, thin size of viitrified 
pa^dng brick. These may be set on edge, to. reduce botli 
the cost and the number of cement joints. It will be nec- 
essary to tie tliis course occasionally to the main wall by 
turning a brick endwise. Kicdi cement mortar should bo 
used and the joints made tliin but tlioroiighly filled with 
the mortar. Such a lining Avould give a surface like a stone 
jug, thoroughly air-tight and indefinitely ]X'rmanent. 

502. Boors. — The jand)s may best be made of 3x6's or 
3x<S's rabbetted two inches deep to receive the door on the 
inside. The center of the jand)s outside should be grooved 
and a tongue inserted ])rojecting threerfourths of an inch 
outward to set l)ack into the mortar and thus secure a thor- 
oughly air-tight joint between the wall and jamb. 

The doors are beet made as described under the stone silo, 
of two layers of matcdied flooring with ])a]i( r between. 



CONSTRUCTION" OF BRICK-LINED SILOS. 

Next to the all-nursonry silos in point of durability and 
efficiency must be raid<ed the masonry lined silos, of which 



404 



tlicrc^ arc sc\'ci"al t_v|)cs,as tollowH: ( 1 ) Stone silos, jacketed 
witli wood; (2) concrete lined >ilos; (.'5) l)ii(d< lined silos; 
(4) lathed and plastered silo.-. 




Fir!. 200.— Sliowiiii;- a brick liiicil rciniKl silo witli hficks scl oii (■<!;;(• mikI 
lilastci'iMl wilii <'cni('Tit. Iii.ls .V. .\ show w lirrc an iron imiI may 
lie lirdili'il ill (lie wall lo iircxciit sprcailiim'. 



Of these tv])i\s the hiick lined silo is likely to come in(o 
the more ii'encial nse, and its c(in>iti'\iction will he (l(\scrihe<l 
first. 



4o: 



503. Foundation and Sill. — JJke the brick silo, this form 
should have a stone, i'ouiidatioai, wherever it is j)ra,ct.i('aJ>le 
to ohtaiii the material for it. Upon this should first be laid 
the sill made of :ix4's cut in two-foot leii,i;tlis with the ends 
beveled so that th( v iiuiy be toe-nailed togethei' and bedded 
in cement nmrtar \i|iiin the wall in the manner represented 
in Fig. 201. The sill is set just far enough back from the 
in^iide of tjie wall so 'that when the bnck an; laid they come 
Hush with the inside (if th<' silo wall. 




I'Ui. 201.— Sliowiiijr iiii'llu"! oi nijikiiitr the sill of lu-ick lined mmiI of round 
wiK.d silos. 15. pinii (1 slmld.ii;; for .-lU-wood. Ip]-jck liiiod or lathed 
iind pl.islered sin. 

504. Setting Studding, — The 2x4 studding are next sc^ 
np and to<'-nailed to the sill. A stud is linst set at each angle 
of the sill, pliunbed and staved from a post set in the center 
of the silo. After four or five of these are set and plumbed 
from the center they shoidd be stayed from side to side by 
tacking to them a sti-ij) of half-inch sheeiting bent around 
the outside ac- high up as a man can reach, taking care to 
get each stud pliunb in this dii-cctioii before staying. After 
the alternate stiuU have been <et up in this manned- the 
inten^ening on<'s may be j)ut in ]>lace, toe-nailed to the sill 
and staved to the rib holding the others in place. 

505. Sheeting.— l^ji,- next step should be to put on the 
outside ]ay( r of .sheeting which, for all of the sihjs Ichk than 

25 



406 

30 feet ill diaiuoiter, should hr tlir(>e-ei_i2,'li!tlis inch luiiiIxT 
made by bm'iiii>' a iiood »|uality of fciiciiii;' and takiiiii; it to 
the mill to liavo it clawed in two. 'i'lic usual })i-ic(' for 
irawing foneiui'' in two in this way is $1.00 pen- thousand. 
The reason for i>"('ttinii,' fcncinii' and havinii' it sawed in this 
manner is to sa\'o expruse. It is the custoui of dealei's to 
eliarge the same jnieo for half inch a^ foi- iiudi lund»t'r, and 
hence buying g'O'od fenc'ina,- and ha\iii,u' it sawctl reduces the 
cost just omvhalf, lees the cost of sawinii'. The studding' 
should be covered iiiside and out with this sheeting-, nailing 
thoroughly with S-pciiny nails, two nails in each bo^ard at. 
every stud. The object of the boards is to act as h<wips and 
give the silo the needed strength. 

506. biding. — If the silo is out of doors it will need to be 
covered with house siding with the thick edge rabbetted, or 
else veneered with a singh' course of bricdc. Several silos 
liave been sided with half-intdi hunber with both edges 
beveled at an angle <d' 4.") degi'ces to take the place of the 
rabbet. This method gives grc^ater strength, hut is not 
likely to kee]) out I'ain as thoroughly. 

507. Lining. — The brick lining of the silo should be laid 
in rich ]\liKvaukc'e, Akron or Louisvilh^ cemeu't mortal', the 
bricks being ]>reviously wet. Tlie most rigid lining will 
be secured by laying the l)rick Hatwise, making the lay(M' 4 
inches thick, but with onedialf the anioiint of hi'ick tluy 
may be set on edge, thus considerably leissening the cost. 
If set on edge, as represented in Fig. 200, a row of sj^ikes 
should be driven into the studding through the joints of 
every fourth course to h(dd the brick more ^ecnrclv in i»lac(! 
until the cement has had time to season. 

The mortar should not be niaih' more than one-fourth (d* 
an inch thick and great care shoidd he taken to leave no 
O'pen sjmce anywhere. The necessity of {dastering the wall 
may be avoided by hlling behind each brick wi'th onedialf 
an inch of mortar, wdiich will kee]) out the air as well as if 
on the front .side and there will be the a<lditional advantage^ 



407 

of tlie cement not coinin<>- in diix^ct contact with tho silage 
jnices. If care is taken in sicttin*;- the l)rick so aH to secure a 
smooth face, pointing the joints carefully, it will not be nec- 
essary to even whitewash the wall and a permanent lining 
requiring no attention will thns he secured. 

In tliis form of silo the brick may have one face tilled 
with coal tar, or the vitritied paving brick may be used, 
giving a lining wholly air tight and jK-rmancn't. 



Kor.Xn PLASTERKD SILO. 

AVhere l)!i(d< are high, luniher low, and clean, sharp sand 
may be readily obtained, a cemenr plastered lining may be 
made to take the ])lace of the brick lining, nsing the Mil- 
waukee, Akron, Kosendale or Louisville cement in making 
the mortar. The first coat is usually made with hair and 
a little lime to make it hang to the wall better. 

There are a good many of these lathed and })lastered 
cylindrical silos in Kacine and Kenosha counties in this 
state, and across the line in Illinois. Some of these have 
been in use since 1S,S!) and have given good satisfaction. 

508. Construction. — The frame work of the silo should 
be made exactly like that of the silo ^vilth brick lining ex- 
cept that there should be two layers of half-inch sheeting 
on the inside with a layer of -J-ply (^iant P. and B. pa})er 
between, or other of as good quality. 

After the woodwork of the silo has been completed it 
should be lathed and ])laytei'ed wi'th a cement mortar made 
of 1 of cement to '1 of sand. 

If wood lath are used there should l)e furring strips of 
lath nailed to ea(di stud u)> and down and rhe lath nailed 
through the-e. If iiietal lath is used this may be nailed 
directly to furring !-tri])s of lath nailed to the studding over 
the lining and the plastering then done. 

It should be understood that it wouhl not do to lath and 
plaster a lectangular wood silo because the springing of the 



408 



walla wcmld crack the ceaneiit. It sliould be iinderetood 
further that on account of the fact that the layer of ceinent 
is so thin it is a niaibter of greater importance to keep the 



d^" tM' 




jrW' 



H 



Pui. 202. — Sbowiiiji' an all-wdud round silo on stone foundation. H rep- 
resents a method of sa\Yini; boards for the conical roof. 



surface whitewashed to prevent the acid from softening the 
cement and rendering it porous. It is because of this alsf> 
that two layers of lining with paper between are recom- 
mended. 



409 



CONSTRICTION OF ALL WOOD SILOS. 

T'j) to the urcsent 'tiiiK- iiKirc silos have be?n built of wood 
than of any other niatenal, and since 181)1, the niajority of 
wood silos hnilt have been after the model represented in 
Yig. 20'2. Very few silos of the rectangular type are now 
bnilt nnle.<s tliev Ive of stone. 



509. Foundation. — There should be a good, substantial 
masonry fouudaition for all forms of wood silos and the 
woodwork should everywhere be at least 1:^ inches above 
the earth to pre\'ent decay from dampnees. There are few 
conditions where it will not be desirable to have tlie boittom 
of the silo 3 feet or more below the feeding floor of the 
stable and this will require not. less than 4: to G ft^et of stone, 
b)rick, or concrete wall. Tor a silo 30 feet deep the founda- 
tion wall of stone should be 1.5 to 2 feet thick. 





fivf|CCP 




Fig. 203. — Showiiif;' two methods of phu-inf? tlip wood, brick lined or 
latlied and plastered silo on a stone foundation. A shows the silo 
set with upper portion flush with the inside of the stone wall, and 
B shows the upper portion flush with the outside of the stone wall. 

The inside of the fountlation wall may be made flush 
with the woodwork above, as represented in Fig. 203 A, or 



■1 1(» 



tlic Imildini; iiuiv stiiiid in llic oidiiijii v wiiv, (hisli willi llio 
outside of llic sloiic \\;ill, ;is rcpfcsciilcd in Ki<>;. 2()-'> \j. Ill 
boil), iviHCS tlic Willi sliniijd lie linislicd sldpiiiii' ;is sliowii in 
tlu' di'iiwiiiiis. 

510. Cementing- the Bottom. A tier the silo has been 
(•(►inpleted the j;riiiind loiinini; llie Imlildiii slmidd he thoi'- 
(Mij^hlv lain|H'<l so as to hv> sidid and then covered with, two 
<ir tlii'ee iiicdies of i>d()d ednt'retci made of I of (•( nienit to li 
oi" 4 ot sand and t;ra\'el. The anioiint of silage wlii(di will 
s|)oil on a liaid clav lloor will nol lie lai'iic, ImiI enou^i;h to 
]r,\.y a. i;'<io(| interest on the nionev invk'sled in I he ('cinieiii 
IN tor. II I he hot loin of I he ;-i jo i:-^ in drv sand or iira\'el tlu; 
cenieiit. Iwnlloin is iiiipeial i\c lo shut. o\it the soil air. 

511. Tying Top of Wall. I n ease the wood portion of the 
silo J'iseis l' I or more tc.'l alxnc the stone work and the 
<1ianieler is niorci than IS feet i'l will he piiideiil lo slav the 
to|> (d I he wall in some wav. 

If the woodwork rises from I he outer cdac of lire wall, 
tlien luiildiiiii' the wall n|> willi <•( incnl so as to coAcr the 
sill and lining' as represented in i^'iii'. 2()T will givo 
the needed slreiiiilh, hccansc the wodd-work will act as Ji 
lioo]); hut if I he silo stands a't the inner face (d' the wall, it 
will he he^t to lav pieces (vf irou rod in I he wall near t he top 
to act as a hoop. 

\\'liei-e I he s'tone |H)rtion <d' the silo is hiu'li euouii'h to 
lU'<'d a door it is Ix st to Icaxc eiiou_i>'li wall hclweieii the toj) 
and tile sill to allow a lie ro(l (d' iron to he heddrd in 'tliis 
portiou. So, too, the lower door in the woodwork of tlu' 
sil<) should lea\'e a full foot in width helow it (d' liiiiilii' and 
siding uncnl to act as a hooj), wliei-e the pressure is 
strongest. 

512. Sills and Studding. The sill in the all-wood silo 
uiav he made (d' a single L'xl, cut in 2-foot l(.ngths, in the 
nianiier represented in Fig. 201 and deserilved under the 
hrick lined silo. 



411 



I lie ^t IhMkiJJ- oI IIiC nil \\(M|(| |(Ullnl mI<i II<vC<I U<,'\. ])<', 

iiir^ci'lliiiii :^x 1 unless the (li;iii)clcr is to exceed '.'>() I'ect, liiil, 
tiu'V slHttild he set ;is close to^ctjier }is omk' fooi froiri (u-uicr 
to center, :i- re)ireseiilc(| in Fig, 201, I!. 'i'liis nniiilter of 
studs is not re(|nii-e(| Jor slrengtli hut tli(;y nn-. )i(^(;de,d in 
order to lirin;^ tlie two hiy''i*s ol' iitiinji- very close tf)get,}i(!r 
so }is io j)rcss the |)}i|»er rdosely iind |ire\cnt iiir Irom c]\\ca'- 
iii^' \vher(! tlie paper 1}||)H. 
A 






. ^ 






•^ 





























. 





O 




. 









Kl<;. JJfM.- Sliowllij.' the (•(.liKliirflioM .,(■ Ilic il>iii|- (or tlii' iill worxl bIIo. 
<i Ih ii rrKHHHfrtiori of the iloor rcHli/i;: ;iKiiiiml the ilnor Jsiriih, wlil<'h 
Ih |irriviil<-<l Willi !i ).'iiwl<''t <if tlii-ff |>l.v nilnToid i-ooUnu iiiid lidfl 
III pliici- with rmir lilt.' lioltM iiiiil ikiihIii'I'm, (Ik- i|iir>r opi'iiliiK on tli<- 
liiMlOr-. !•' Ik ;i Ironl vli-w of III.- (lour iriiidc of two lii.v<T« of four 
Inch or kIx Inch loii(.'ii<'(l iiiul ki'oovciI (lorii-lMK vvllli :i hi.vcr of tliri-c- 
ply iicid iinit Wilier proof )'. \- 1',. [liiiicr licl wci-n. 



To Httav the studding' ;i, post ,-lioiild he set, in the ground 
in tlie, ceriP^r of the silo lon^' enough to reach iihrmt 5 fitcX 
above dio sill find to this st-avH niay Ik- nailed \a> hold in 
phic<. the alt<-rniitr -tiids nntil the lower 5 feet of outside 



shicct.iiii;' li;is Ix cii piil (Hi. 'I'lic -IikUsIkhiM h" set lir.-l ;il, 
tlio iiii^'lns I'oriiicd in tlic sill ;iii<l ciirct'iilly slnvcd ;iii<l 
])'lunil>('d, (HI the side towiird llic cciiler. Wli.cii ;i miinlMT 
ol" llicsc liiivc Ix'cii scl llicv should he lied l(>i;( 'I hi'l' h_V 
hctidiiiii- ii' slri|» i>\' hidl' Iiudi sliciil iiii!, aioiiiid the outside.' as 
Jil<;li up as a luau can reacdi, lakina,' care to |)linnl» eatdi stud 
on tJu^ side l)(>:fore nailiuf;-. When I he altrrnate s'luds have 
IxH'ii set ill this way the halance may he placed and toe- 
nailed to the sill and stayi'd lo'llic I'ih, iii'st phnnhiui^' them 
sideways and to\\ai'<l the center. 

()n the sidei of the silo where the ddors ai'e lo he ivlaced 
tlio siuddiuf;,' should he set douhle and the distance ajwirt. to 
g'ivei the desired width. A stud should he set hetween the 
t.wo' d(!or studs as ihouiili no door were to he there and 'the 
doors cut out at the places desired afterwards. M'he con- 
stiMielion (d" the door is represeiite<l in Fig". ^0 1. 

513. Sheeting and Siding-. — 'I'hc eharaeter of tJie siding 
and shcetiui;- will vary (^onsiderahly aecoi'diuiij to ('.(Mulitions 
and si/.(^ of t he^ silo. 

Where the diameter (d' the silo is less ihan IS fed inside^ 
and not niu(di attention iieeil he paiil lo ti'ost, a siuiiie layer 
of l)e\'(de(l sidiui;', I'ahhetieil on llie inside <>( the thick edo-e 
do!("|) -enoujiii to receiixc the ihin e(li;i' n\ ihe hmii'd hehnv, 
will he all that is ahsolutely neeessary on the outside toi* 
streuiith and pi'otection ai;ainsl weather. This statement 
is made on the supposition llial the lininii' is made (d two 
layei's (d" fencinii' split in two, the three layers const it lit iui;' 
t hie hoops. 

If the silo is larger than IS feel inside diameler, there 
should h(^ a layer id half iiitdi sheeliiii;- oirtside, under the. 
sidiiii;'. 

If hasswood is used lor sidiiiii eare should he. taken to 
paint it at once, otherwise it will warp hadly if it ••'ets wet 
before > paiiitini;-. 

Ill applyinii,' the sheeting' heiiiii at the hotl(Uii, carrvinf» 
the work upward until staiiiii*;" is needed, f(dlowin<i' this at 
once with the sidiuii,'. 'i'wo S-pciiny nails should he used 



4 1 :'> 



ill. cjicli liojii'd ill cN-crv shid, ;iiiil !(► prcNciil tlic \v;ills from 
iictt iiii;' "out ol roiiiKr' I lie siicccccling i-ourscs of Ixjurd.s 
sliouifi Ix'iiiii oil the next -hill, fliiirt iiiakiii«i' tlic ciuU of tho 
boards hi'icak joiiifs. 

When tine staf;iiii;s arc put ii|) ik'W >l;iys slioiiM \\r 'lacked 
to the studs alutx'c, lakiiii;' ciiK to pliiiiih ciudi one Iroiii 
sid(» to side; tlic siding' itself will l)riii<;' 'tlieiii into |)laex! and 
kcc)) tliciii pliiiiil) the, otlier \va_v if caic is taken to start iiiew 
coiii'-es ;is deseiilted al)o\'( . 

514. Forming the Plate.- -When the last sta«>,ino- is up the 
jdate should l»(^ foniied Ivv spiking' :^x4's, cut in two-foot 
leiifiths, in the iiiaiiincr ol" the sill, and as i"e|)resent.ed in. Fig'. 
205, down upon the to])s of the studs, usini;' two courses, 
inakinu' the -second hiejik joints with the liist. 




l-'li;. 2<ir).- Slii/W iiiK i-i>Msiriictliiii ol' coiih-mI i-imr of roiinil sIId wlicrc riil'lcrs 
arc iiDl iisr<l. Till' Diilfi- cii- ■!(• is llic lowi-r cdKC of (lie pool", IIk; 
sci-oi).(l circle is the plate, the lliii-il ami foiirUi circles .-ii-e hoops 
to which the roof hoai'ds afc ii.iilcd. The view is a ])laii lookititc up 
fiTim the ii;iilcr siilc. 



515. Lining for Wood Silos. — Tluiro are several ways of 
making a good lining for tiic all wood round silo, but 
whicli(!Vor method is a<lopted it must ])e kept in mind that 



414 

there are two A'ery i]n|)ortant ends to be secured with cer- 
tainty. Tliese are (1) a lining which shall he and remain 
strictl}" air tight, (2) a lining ^\'hich will be reasonably 
permanent. 

Galvanized Iron in Silo Lining. — The tightest lining for 
a wood silo may be made w^ith a light weight of galvanized 
iron, ]S[o'. 28 to l^o: 32. Where the silos are 18 feet in 
dia.nieter or lees this may be ]nit directly npon the studding, 
buying the strips 8 feet long and ;5H inches wide, so as to 
be nailed on up and down and exactly cover the sj>ace be- 
tween three or four studs. Headers, should be pul in every 
8 feet to nail the ends of the sheets to between the studs, 
and these are best when sawed to the curve of the silo. The 
inetial should be put on with roofiug nails, nailing close so 
as to make the joints tight. 

After the metal is in place it should be given a heavy 
coat of asphalt paint, taking special care to make it heavy 
where the nails and laps come so as to shut out the air. 

When the metal is in place and painted it should be 
covered with a layer of sheeting made the same as that used 
outside, by splitting good fencing in two. The object of 
this layer of sheeting is, first to take the pressure of the 
silage; second, to act as a hoop for strength, and third, to 
kee]) the silage from softening and wi])iug the ]iaiut from 
the metal lining. Were it not for the fact that the heat of 
the silage tends to soften the paint, and its settling to wipe 
it off, it would be better to let the metal come next to the 
silage. 

Where the silo is more than IS feet in diameter it will be 
best to use two layers of fencing split in two, placing the 
galvanized iron between the two layers. In these cases the 
sheets of metal may be put on horizontally, using those 36 
inches wide. 

All Wood Lining of 4-inch Flooring — If one is willing 
to permit a loss of 10 to 12 per cent, of the silage by heat- 
ing, then a lining of tongued and grooved ordinary 4-incli 
white pine flooring may be made in the manner repre- 
sented in Fig. 206, where the flooring runs up and down. 



415 



When this hiiiihcr is |)ut on in the seasoned condition a 
single hiyer wouhl make tighter walls than can he secured 
with the stave silo wliere the staves 
are neither heveled nor tongued and 
grooved. 

In the silos smalk-r than IS feet in- 
side diameter the two layers of boards 
outside will give the needed strength, 
but when the silo is larger than this 
and deep there would ])e needed a 
layer of the split fencing on the inside 
for strength ; and if in addition to this 
there is added a layer of 3-ply Giant 
P. and B. paper, a lining of very su- 
perior quality would be thus secured. 

Lining of Half-inch Boards and 
Paper. — Where paper is used to make 
the joints between boards air tight, as 
represented in Fig. 207, it is ex- 
tremely important that a quality 
which will not decay and which is 
both acid and water-jn-oof be used. .V 
paper wdiich is not acid and water- 
proof will disintegrate at the joints 
in a very shoi't time and thus leave the 
lining very defective. 

Great care should be taken to have 
the two layers of boards break joints 
at their centers, and the paper should 
lap not less than 8 to 1 2 inches. 

The great danger with this tvpe of silo where tiie lining is made 

^. . -Ti 1 T 1 1 ofordiuary tour inch noor- 

lining W'lll be that the boards maV not ins running up and down, 

, , „ '^' and nailed to girts cut in 

press tne tw^O layers OI paper together between the studding every 

close enough so but that some air may 

rise between the two sheets where they 

overlap and thus gain access to the silage. It w^ould be an 

pxcellent precaution to tack down the edges of the paper 




Fig. 206. — Showing the 
construe' ion of the all-wood 



I 1 



closclv witli small carix't tiK'ks wiici'c tlicv oNcrlap, and if 
this is (loiic a lai» of 2 iiiclics will he snilicicnt. 




Fii!. 3)7. I>. Sliowiiiii' iiu'llioil or isl riicliiij:- Ihc !ill-\vo(iil roiiinl silo 

iiiul cDiiiiccliiiK i( with Ihc \v;ill llnsli wilh Ihc onlsiilc. This t\)i\\ro 
sliuws Ihc iiiosi siilistiiiil iiil I'nriii nl' ciiiisl ruclloii with three liiycM's 
(if li;ill-iiiili liiinlpcr Mil. I two l.MVci-s ol' I lircc ply jicid Mini water 
lirool' I'. iV- r>. |iM|)er iielwcen llieiu. A very excellent silo is iiiMile 
al'tei- this jilMii oiniltini;- ihc inner iMyer of liiiiiin mikI paper and 
tlie layer of pMpcr on Ihc oulsiile. With siiiMll silos Ifi I'eet in diaiii- 
elcr (inly 1 lie siding >>ii Hie oiiiside is neccssMry I'or slrcn};ih Mini 
lirotcctiiin a!;Minsl weather. I'l. Showinu' method of const rnel ion for 
venlilalinj; the spaces hctween tlie stnddiiii;- in all-wood and lathed 
Mild piMstered silos. The tower portion shows the intakes of fresh 
air fron; the oiitsid(» at the lioltoin. and the npper portion shows 
wliert> Hie air enters tli" silo at the plate to pass out at the ventilator 
ill I fie roof. 



Siicli a liiiino' as this will he very iliirahlc' hci'ansri tlio 
pajMT will kc('|> all \\\r liiiiihcr drv except tlir inner layer 
of lialt'-inch hoards, and this will he kept W( 4. hy the paper 
and silaii,(i until eini)ty and then the small thi(d<iiess of wood 
will dry too (iniekly to jn'rinit rottini>' to s(>t in. 

A still iiionp substantial lining- of the same type may be 
secured by using- two lay<M-s of ]ia]H>r between iln'ee layei'S 
of boards, as roprosented in Fig. "207, and if the climate is 



417 

not, oxtreriicly s»v(-i'c, or if the -ilo i- only to ]>■ f< (| from 
in tlio KuinnuT, it would Ik- l.ctici t<i do Hway with tlic layer 
of slicotiii^' and jtaiK-r oiit-ii|c, jdittin^ it on the inside, thufe 
s<'('iirin<:- two layci's of jiaitcr and tlircc layors of Itoard.s for 
<\\n- liiiinji- with fho c^inixah-nt of only 2 intdics oi' liirnWir, 

516. Construction of Roof.- 'I'lu; roof of cylindrical siloH 
may Ik- ni;ido in -oxr ral way-, hut the siinplc-t type of con- 
struction and the one uHjiiiiin^' thf^ leaHt arnoimi of mater- 
ial is the cone, represented in 1' igs. 202 and 20."». 

If the silo is not larp-r than 15 feet insid(; dianietx-r no 
rafters need he used, and only a single circle, like tliat in 
the center of Fig. 207, I). This is made of 2-inch stuff cut 
in section in the foi-m of a circle imd two layers spiked to- 
gether, hreaking joints. 

517. Ventilation of Silos. Kvery silo which has a roof 
shoidd he jtrovided with amph? ventilation to kee|> the 
undf-rside of rhe roof dry and in tln^ case of wood silos, to 
prevent tin- walls and lining from rotting. One of the 
nio.st sei-ious mistake- in the early con.stniction of wcxwl 
filcjs was the making of the walls with dearl-air spaces 
which, on accrumt of the dampnes- from the ~ilage, lead to 
rapid "dry rot" of the lining. 

In the \v(H)<\ -ilo aiid in the brick lined silo it is irnfx^rtant 
to provifle ample ventilation for the spaces lK;twrif?n the 
.studs, as w(dl as for the roof and the inside of the silo, and 
a g(Kjd method of doing this is n^jresented in Fig. 207, E, 
where the lower portion represents the sill and the upper the 
plate of the silo, lietween each pair of stnds, where needled, 
a one and one-fourth inch auger hoh^ to admit air is hored 
through the siding and slx-eting and covere<l with a piece 
of wire netting U> kf^ep out m'loa and ratH. Ai the t/jp of 
the silo on the inside the lining is only r^overed to within, 
two inchfis of the plate and this sparse is covered "with wire 
netting to prevent silage from })eing thrown over when 
filling, 'i'his arrangement jyarmitH dry air from outside to 
enter at tho bottom between each pair f/f sturls and to pass 



418 

u)) and into the silo, thus k('{'])iiii;- th<' liiiiiiii' and studding' 
dry and at, the same time drving the undrr side of the root" 
and the inside of the lining avS fast as exposed. In those 
c^S'es where the sill is mach^ of 2x4\s eut in 2-foot lengths 
there will be sj)are enough left between the curved edge 
of the siding and sheeting and the sill for air to enter, so 
that no ho[es need be bored as (h'scribed above and re])re- 
sented in Fig. 207 E. The ojienings at the plate shonld al- 
ways be provided and the silo should have some sort of ven- 
tilator in the roof. This ventilator nia_y take the form of a 
cupola to serve for an ornament as well, or it may he a 
simple galvanized iron pipe 12 to 24 inches in diameter, 
rising a foot ov two through the ])eak of the r<M)1. 

518. Painting Silo Lining. — It is impossible to so paint a 
wood lining 'that it will not beconu^ wludly or partly vsatur- 
ated with I he silage juices. This hieing true, when the 
lining" is again exjvosed when tceding the silage out, the 
paint greatly retar<ls the di-ying of the \vo(k1 witrk and the 
result is decay sets in, favored hy the ])roIonged dam])ness. 
For this reason it is best to h^ix'e a wood lining nake(l or to 
use some antise|)tic which <loes not loi'iii a water ])roof coat. 



TIIK STANK Oi; TANK SII.O. 

Wc! have examined j)ei'sonally tll(^ ])ast season 1!> stave 
silos and liave made a careful study of the unavoidable 
losses in one ol" these. We have also studied tire unavoid- 
able losvses in two kinds (d" small stave silos. .\s a result of 
these obvservations it Ims heen demonstrated that there ai"e 
several very senious objections to stav(> silos intended as ])er- 
manent huildings out of dooi-s. Some of these are stated 
below: 

1. When the: silo is empty the staves sliriid< and loosen 
the lioojis and in this condition the wind racks the building, 
getting it out (^f round, out (d" ])lumb, and out of ])lace u])on 
the foundation. It is nuudi more easil\- blown down tlian 



410 

o-tluM' fdiiiis of silos. 'I'wo of the foui-tci'ii oirf-of-(|()or nilos 
visitt'U had \>vvi\ Mown down; one (»f these was abandoned 
and the hoops sohl to aiiotlier farniei-; the other was set up 
aiiain at the expense o-f a (Uiy's (h'ive for new staverf and j»(^t- 
tiiiii' the carpenters to set it np, tlie aceich'iit ha]>peiniii>' just 
as they weie ready to till 'the sil<» last fall. 

A third silo of the fourteen out-of-doors we visited liud 
moved on the foun<hitio:i so mneh tliat I could put my arm 
up tlu'ouii'li hetween the stone wall and the outside of tho 
staves. This sih* had heeii staye<l to the ( iid of the harn, 
using' fence wire for guy i'o<ls. 

Three others of tiie fourteen out-of-door .stave silos had 
been found so unsatisfactory that they were subsequently 
lined on the inside to pi-event th(^ sila^'e from spoiling, and 
in two id' these three the inner lining lias rotted out on ac- 
count of the dainpiu-s whi(di the outside staves confines. 

2. riiei'e is gi'eat danger of the hooj)s being broken by 
the intense pi'cssui'e of the silage increased by the swelling 
of the staves. In one of the silos visited eight out of ten 
li(K»ps on one side of the silo and six out of ten on the o])])o- 
site side had sheared in two the j!x4's used for lugs; j>ut, by 
a fortunate coincidence, two of the ten hoops remained 
intact to hold the silo u]), assisted by some half-inch boards 
Avhich had been bent around the inside of the silo at the top 
to prevent the staves from falling in. 

In another silo where 4x4 oak ])ieces had been used as 
lugs, the i;-iii(di iron washers had been crusheil their full 
dejrth of one-half inch into the hard wood and tw'o of the 
])ieces of wood lia<l l)een badly injured by the severe strain 
u})on them. 

Tn a f(Mirth silo where the hoo|)s were provided with iron 
lugs the staves on one side had been thrown into the silo by 
the sw(dling of the wood. 

It is urged by the advocates of these silos that with a 
little care and judgment the nuts of the^ hoops may be 
tightened or loosened as needed and such accidents averted. 
There is enough truth in this statement to induce many 
farmers with liniite(l means to take the i-isk, but life is too 



420 

sli'Oi t iiiul 'llici'c lire too iiiaiiv other tliiii_i;>; to ciiui'o.ss tlic nt- 
tciitioii of i;<w)(l fanners for tlieiii to lie awake: nijjlitci wou- 
doriiig wlietlier the sihi hoops are toi) tii>,"lit or to loose. 

3. Staves do not eoiitain the same ainomit of ©apwood in 
all parts and for tliis reason shriidc nnecpially, with the re- 
sult that after -'5 o^r 4 years' use there are places which do 
not clone up tig,'htly on swellinii; and whicdi oi>eii again on 
'the sunny side of the silo, and thus admit air, even where 
the silagie is in contact Avith them. 

Three of the silos visited showed these jiecidiarities, and 
in one of tlieni visited last winter we couhl see thVouiU,h be- 
tween several stax'cs on the south side (d' the sih» close to the 
silage surface, on the inside. 

4. The expansion and conti'action of the staves duriui;;^ 
wetting by the silage and drying when the silo is einpty 
makes it dithcult to securely anchor a ])erinan.ent roof and 
impossible t(> connect the staA'cs permanently with the foun- 
dation, so as to be air-tight. Something must be done each 
season to ceinent the joints Ix'tween the staves and fonn- 
dation or air will enter. 

5. There is no reason to hope thai good silage with snudl 
losses ,in dry nuilter can he made in the stave silos which 
are not cai-efully constructed (d good IuiuIkm- Avith the 
staves both beveled, aiul tongued and grooveil. It is I'eally 
more difhcult to make a stave silo air tight than it is to 
make a tank water-tight, and we have found by carefni 
tefttsthat the unavoidable losses in a new stave silo next to 
the walls were: as high as 24 to 2cS |)cr cent. 

519. Construction of Stave Silos, 'idiere ar(^ three meth- 
ods adoj)ted in the construction cd" these silos. The; best 
and only one which should be used in the ]h rnuinent siK> 
is that represented in Fig. 208, where the staves are both 
beveled and tongued-and-grooved; the second is where the 
staves are beveled so that the Hat surfaces Hi together ac- 
curately as water tanks are nmde; the third ])laji us(\s the 
lumber without, either lievc'ling or tonguing-and-grooving, 
and this both observation and principles of construction in- 



421 



(licatc slioiild lie ;i(l<i|ifc(l with Ncry grt-at licsitatii^u and as 
a toiiijtorai'v uiakcsliit't (uily until more experience and ex- 
act kiiowlcdiic lias liccii ohtaiiicd T('i>'ardino- fhoir perma- 
nent {■tiicicucv. 




I'"n;. 20JS. — SiKiwiiif;- ilic ci.iisrrui lidii nC ilic sliivc silo. A sliows Hit- sili> 
oimiplftc on stdiic f()iii!<l;it ion with four fccdin.;;' doors. 1? is cross- 
scctioii of four siiivcs sliowiiifi liow llicy arc toiiu'ii'd and jcroovt'd 
to niak'' tlicm air U};ht. (" sliows a nictliod of spliciufr staves. D 
sliows iron ]u«s for tifilitciiiiij; lioojis. F is front view of door viewed 
from oiilside. (i cross-seel ion of same. K is a vertical section sliow- 
inji tlie sliouliler afiaiiist \\ liicli the door rests, and upon wlii<'li should 
l>e a trasicet of tlii-eeiily rulieroid rooting,'. 'IMie door slionld also lie 
<lrawn li^lit ajiainst it with four la;;- Ixdts and washers, opening from 
the inside. 



'J'liis third |>laii ha.s hccu rceouiniendcd he(^au!-ti the first 
cost is relati\( ly hiw and because it is assumed that the pres- 
2G 



422 

siiro duo to tlio swclliiii;' (if the wooil iind tlic liiiiditv of tlu; 
HoQps will result in criisliiiiii' the cdiids (d" tlu' t^taveis to- 
gether so as to uiakc a sutliciciitly tiolit ji>iiit to pivscrve 
the silage. 

520. Lumber for Staves.- -T lie linuLer s(dectod for the 
staves of this t\})e of silo should he (d' the <>Tade knowu coui- 
luereially as "tank stiitf," and luiidtci' fircst from knots 
and steaightest giaincd is host. Wood is (piite air-tight 
undei' low ])re^ss^l^('s in directions aci'oss tlic giain Invt along 
the grain tlu^ air passrs nioie oi less freely. The \Va.shing- 
ton eedar appears to he an excellent wood for this ])uri)(xse, 
as it shrinks nnudi hss than the pine attcr the silage is re- 
moved and, ftn'this rcasdii, tlic hnilding will he nnudi more 
stable when cmpt\' and U'ss jiahlc to hurst tlic hoops when 
tilled. 

Where the silo is to he deepc r than can readily he secured 
with singh' lengths of lund)cr thc! staves may he spliced in 
the manner represented at ( ■, Fig. 208, where a saw-cut is 
made in the ends of the two staves and a })ieee (d' galvanized 
iron, a little wider than the stax'c is sli[)ped into it. Thi^ 
ernshes into 'tlu' wood dii the sides and forms a water tight 
joint. 

521. Foundation of Stave Silo. — Ou account of the ten- 
•deney of the sta\'e <ilo to work otl" from the wall when 
empty a Hat c('nient tloor has heen rei-ommended, made of 
sand and graxcl or ciusiu d ro(d<, fonidng a hed of conereto 
abou't 12 inches thick. This is p( rliaps as godd as can he 
done under the ciicunist;inces hut it precdiuh's the exten- 
sion of the silo into the groun<l. 

Tf tlu'i si hv stands upim a stone wall, as ripresented in F'ig. 
208, it will he ])rmlent to have a shoulder jutting into the 
silo as nnudi as 2 inches and a similar amount on the out- 
side, to permit of some movement on the founchition. 

522. Hoops for Stave Silo.— Five-eighths inch round iron 
roils, in ahout l(i-foot lengths, form the Ixst hoops and they 



423 

should lie |»r(ivi(l('il witli loui;' tlii'cads and JoIiumI with iron 
lugs and nnts, as rcprosonted in 1), Fig. 208. The iron lugs 
sliouid aiwavs he u^i'A in pi'id'cicncc to the 2xl's oi- -Ix4's 
because th(y aie het'tcr in cvciv wav. So, tod, should thev 
b(^ us('(| in |>i I'l (iciirc ill pi.sts set up al;ain-^t the sih) outsi(K' 
or sha|)('d to act a< a part of the slaxcs as has hrcii reeoni 
mended. In \isitiiii: o\( v 100 sihis in istM it was found 
tluit whcicvci a sih) liniuii had a hca\v tindicf hack of it, 
the holding ot danipncss cansid totting there in three or 
four years, and il i- ipiil.' <'eilai!i thai the use df iion lugs 
is the; safest way to a\oid ihi- danger in sta\'e silos. 

523. Doors for Stave Silos. — A good method of construct- 
ing d(^(>rs for the stave silo is represented in Fig. 208. 
Two inch hiniher is holtcfl to the staves on the outside, pro- 
jecting two in<'iies into the doorway all around, thus form- 
ing a rahliet against which the door may rest. A strip of 
thick rtdx'roid rooting shonhl he nse<| on the rahhet under 
the door and the door drawn down tight with four lag holts 
and wa.shers. 

A common way <il making the<e ilnurs is to cut the staves 
out on a lic\'el and make tli." door til into lhi< Weveled cut 
directly. Il'tli! w.n k is car(d'ully done and t hen, at the time. 
of tilling, if the face of the In \cl i> |)lasitered with a tliick 
coat of puddled (day and the duor i'nvm] lightl\- into this a 
fairly <do-e |oint ma\ he -ecnre<l. 

524. Pit Silos. — In localities where h-.th Imnher and 
m'a-soniy are ex|)ensive or cannot he had, and w here the soil 
is of such a character that a ])it 15 to 20 feet deep may l)o 
sunk in the ground, a good silo may l)e made in this way. 
The most s(ii(in- ohjectioii to sncdi a sihi is the incon- 
venience of remo\iiig the >ilage to i\ i(\. 

If the soil is of such a charactei- that it will not cave in 
tlie i)it may he ma<Ie circular in form, of the desired size 
and depth and tlien plastered with cement in the manner 
of a cistern. 1 f tlieie is a little dillh-nlt v in t he walls stand- 



424 



iiig the ])it iirav Itc iiuidc with slopint;' sides, snuillcst at the 
bottom. 

Fii using- such a, siht, (speciality vvlieai filling it, care slioukl 
b( (il»serv(H] in going into it when there is n possibility that 
carbonic acid has accnnmlated to' a dangerous extent. There 
need be no danger in using su(di a sihi if caulidu is observed 
as stated on i)age 427. 

525. Weight of Silage per Cuhic Foot. — Tlie weight of 
corn silagci increases with the depth ])olow the surface, with 
the amount of water in '[he silage, and with the diaineiter of 
tliei t'ilo. In silds of small diameters the amount of surface 
in the wall is so mucdi greater in proportion to the silage 
contained 'that tlu' fi'icti(ui on the sides has more influence 
in piexcnting the si ttling of the silag-e. In the following 
table will be found the weights of silage per cubic foot in 
round silos given lor different depths and 'the mean woig'ht 
of silage aboAc the given depth: 

Table K/ioivi,ng the computed weight of well matured corn sil- 
age at different distances below the surface, and the com' 
puted mean weight for silos of different depths, tiro days 
afte.r filling. 





Weiglit 
of sil- 
age at 
dift'or- 

ent 
depths. 

Lbs. 


Mean 




Weiglit 


. Mean 




Weight 


Mean 


Depth 


weight 


Depth 


of silage 


weight of 


Depth 


of silage 


weight of 


of 


of sil- 


of 


at 


silape 


of 


at 


silage 


silage. 


age per 


silage. 


diflPerent 


per cubic 


silage. 


difiFerent 


per cu. 




cu. ft. 

iTbir 


Feet. 


depths. 
Lbs. 


foot. 
Lbs. 




depths. 


foot. 


Feet. 


Feet. 


Lbs. 


Lbs. 


1 


18.7 


J8.7 


13 


3< 3 


<;8.3 


25 


51 7 


36.5 


2 


20 4 


19.6 


14 


38 7 


29.1 


26 


.52.7 


37.2 


8 


22.1 


20.6 


15 


40.0 


29.8 


27 


53.6 


37. £ 


4 


2S.7 


21.2 


16 


41 3 


30.5 


28 


54.6 


38.4 


^ 


25.4 


2i.l 


17 


42 6 


31.2 


•^9 


55 5 


39 


6 


27.0 


22 it 


18 


43.8 


31 9 


?Q 


,53.4 


39.6 


7 


28.5 


23.8 


19 


45.0 


32 6 


31 


.57.2 


40.1 


8 


30.1 


24.5 


20 


46.2 


33 3 


32 


r8 


40.7 


9 


31.6 


25.3 


21 


47.4 


33.9 


33 


58.8 


41.2 


10 


33.1 


26.1 


22 


48.5 


34.6 


34 


59 6 


41.8 


11 


34.5 


26.8 


23 


49.6 


35.3 


35 


60.3 


42.3 


1:2 


35.9 


27.6 


24 


50.6 


35.9 


36 


61.0 


42.8 



526. Capacity of Silos. — The amount of silage which may 
be stored in a silo iucieases in a higher ratio than the dc'pth 



425 



incre;i>'e.>^. .V silo oO feet dec]) will .-tore nearly ."> times llio 
anioTint of feed that one 12 feet deep will. 

l)onl)lin<;' the diameter of a silo increases its eapacitv 
more than fonifold and a silo :')() feet in diameter will hold 
more than S) times as mn(di as one 10 feet in diami ter and 
of the same d(>])th. It is (deai' from this that small silos 
must he I'elativelv mor<' eostiv that those of larii'ei- diameter. 



Table giving the approximate capacAtij of cijlindrical silos for 
well matured corn silage, in tons. 



Depth, 


Inside Diameter in Feet. 


Feet. 


15 


16 


17 


18 


19 

94.41 
ICO. 9 
107.9 
115.1 
122.1 
129.3 
1.H7.1 
144.7 
15;i 4 
160.3 
168.4 
176.2 
184.6 


20 


21 


22 


23 

138.3 
147.9 
1.58.1 
168.7 
179.0 
1S9.5 
200.9 
21i.0 
223.3 
234.9 
246.8 
258.2 
270.5 


24 


25 

163.4 
174.7 
186.8 
199.3 
ill. 5 
.'23.9 
•37.4 
:;n0.5 
63.9 
!77.6 
91.6 
05.1 
319.6 


26 


20 

21 

22 

23 

24 

25 

26 

27 

28 

29... 

30 

31 

32 


58.84 
62.90 
67.:^5 
71.73 
76.12 
80.6^ 
85.45 
90.17 
91.99 
99.92 
105.0 
109.8 
115.1 


66.95 
71. 56 
76. 5i 
81.61 
86.61 
89 61 
97. 23 
102.6 
108.1 
113.7 
119.4 
121.9 
135.9 


75.58 
80.79 
86.38 
92.14 
97. ?8 
103.6 
109.8 
115.8 
li2.0 
128.3 
134.8 
141.1 
147.8 


84.74 
bO.57 
96.84 
103.3 
109 6 
116.1 
123.0 
129.8 
i:-;6.8 
143.9 
i51.1 
1.58.2 
165.7 


101.6 
111.8 
119 6 
1V7.5 
135.3 
143.3 
151.9 
160.3 
168.9 
177.6 
186.6 
195.2 
204.6 


115.3 
123.3 
131.8 
140 6 
119.2 
158.0 
167.5 
176.7 
186 2 
19.1.8 
20.) 7 
215.3 
225.5 


126.6 
135 3 
144.7 
1.54.3 
163.7 
173.4 
183.8 
194.0 
i!01.3 
214.9 
•^25. 8 
236.3 
247.5 


1.50.6 
161.0 
172 2 
183.6 
191.9 
208.4 
218 8 
230.8 
243.2 
255.8 
268.7 
281.8 
291.0 


176.8 
189,0 
202.1 
ifl5.5 
2'<d8.7 
242.2 
256.7 
270.9 
285.4 
cOO.2 
315.3 
330.0 
345.7 



111 this table the horizontal lines give the nnmher of tons 
of silage held l)_y a silo having the depth given at the left 
of the eolnmn. 



527. Horizontal Feeding Area. — In the construction of 
silos it is very important to have the horizontal dimeui^ions 
sucli that tlie rate of feeding shall he ra])id enough not to 
permit moulding to occur oii t\\v> ex]>osed or feeding sur- 
face. It is also important to have the horizontal dimensions 
as large as jiosyihle Ix'cause the larger the silo is the less it 
costs in ])roportion to the feed it stores. Then, too, nan'ow, 
small silos (lo not alloAv the silage to settle as well, and hence 
in them the necessary losses are proportionally greater 
than in the larger ones. 



426 



Observations indicate that if silage is fed down at a rate 
slower than 1.2 inches daily, moulding is liable tO' set in. 
This is more likely to be true in the np})er half of the silo 
than in the lower half l)ut it will be ]n-udent to have 'the silo 
of such a diameter as to lower the surface more rapidly in 
feeding than is nece^saiy rathei- than less rajndly. 

A silo 30 feet deep will allow 1.5 inches in de]irh of silage 
per day for 240 days, and one 24 feet deep will allow 1.2 
inches for the same time. From the table on page 424 it 
will be seen that the mean weight of silage per cubic foot 
for a silo 30 feet deep is 39.0 lbs., and allowing 40 lbs. of 
silage per cow per day it is seen that a cubic foot of silage 
on the average will feed a co^v one day. But from the 
same table it will 1)e seen that if the silo is 24 feet deep 
there will l)e required 1.1 14 cnbic feet of silage to give the 
desired weiffht. 



Table giviuf/ the inside diameter of silos £4 feet and SO feet deep 
luhich will permit the surface to he lowered in feeding at the 
mean rate of 1.2 tolii inches per day, assuming 40 lbs. of sil- 
age to be fed to each coiv daily. 







Feed for 


240 Days. 




Feed for 


180 Days. 


No. OF 
Cows. 


Silo 2U feet deep. 


Silo 30 feet deep. 


Silo iUfeet deep. 


Silo SO feet deep. 


Rate 1.2 in. daily. 


Rate 1.5 in. daily. 

1 


Kate 1.6 in. daily. 


Rate 2 in. daily. 




Tons. 


Inside 
diameter. 


Tons. 


Inside 
diameter. 


Tons. 


Inside 
diameter. 


Tons. 


Inside 
diameter. 






f^. in. 




ft. in. 




ft. in. 




ft. in. 


10. .. 


48 


11 11 


48 


10 2 


36 


10 4 


36 


8 9 


15 


72 


14 7 


72 


12 5 


34 


12 8 


54 


10 9 


20 


96 


16 10 


•96 


14 4 


72 


14 7 


72 


12 5 


25 


120 


18 10 


120 


16 


90 


16 4 


90 


13 10 


30 


144 


20 8 


144 


17 6 


108 


17 10 


\m 


15 2 


35 


168 


22 4 


168 


18 11 


126 


19 4 


126 


16 4 


40 


192 


23 10 


192 


20 3 


144 


20 8 


144 


17 6 


45.. .. 


216 


25 7 


216 


21 5 


162 


21 11 


162 


18 7 


50 


240 


26 8 


240 


22 7 


180 


23 1 


180 


19 7 


60 


288 


29 2 


288 


24 9 


216 


25 3 


216 


21 5 


70 


336 


31 6 


336 


26 9 


252 


27 4 


252 


23 2 


80 


384 


33 8 


384 


28 7 


288 


29 2 


288 


24 9 


90 


432 


35 9 


432 


30 4 


324 


30 11 


324 


26 3 


100.... 


480 


37 8 


480 


31 11 


360 


32 8 


360 


i,7 8 



Using these data tlic iii>i(l(' (liaincrcr of cvliiidi'ical silos 
24 feet and 30 feet deep which will hold feed enoiiii'li for 
diif(n*ent nnnibers of cows may he coniputed and sncdi re- 
sults are given in the preceding' table. 

528. Danger in Filling Silos. — It never should be forgot- 
ten in connection with the lilling of silos, that carbon diox- 
ide is generated very rapidly the first few days after sil- 
age is pnt into the silo, and it sometimes happens if the 
air is very still over night, and if the surface of 
the silage is a considerable distance below any door, that 
carbonic acid accuninlates in sufficient quantity over the 
silage 'to make it impossible for a man to live in it. (Jases 
ao-'e on record where people have been suffocated by going 
into a silo under these conditions. If the doors in a silo are 
so close together that a man standing on the silage Avill have 
his head above an open door the carbonic acid gas will flow 
out of the door and not accumulate to such an extent as to 
be injunous. 

In causes where the silage is below any opening far enough 
to leave a man's head below tlu^ o]>ening care should be 
taken not to go into the silo in the morning after filling has 
begun until after the machinery has been started. After the 
silage has been dropping into the silo for a few minutes it 
will stir the air up sufficiently to render it pure enough for 
a man to work in it without danger. Ordinarily the air 
cuiTcnts outside are sufficiently strong to prevent the car- 
bonic acid from accumulating, but it should be kept in 
mind that it is possible on still nights for this accunmla- 
lation to take place. 



428 



FARM MECHANICS. 

CHAPTER XX. 
PRINCIPLES OF DRAFT. 

Tt" it wero jxtssihlc to constnict ;i pci'tcct road its leiigtli 
would be the shortest distance between the places con- 
nected, and it would offer no resistance to movement over 
it. A pair of ])arallel, level, smooth and rigid steel rails, 
well bedded, constitut(^s tlie nearest approach to the perfect 
road yet devised, and how vastly superior the steel track of 
the railroad is to the best ])aved street is shown by the 
enoniious loads moved and liii;li speed attained over them. 

529. How the Draft Increases With the Grade.— A ])ull of 
2,000 lbs. is required to lift a ton vertically, but to simply 
move it horizontally only the friction of the carriage and 
the resistance of the air need be overcome. The more 
nearly level that roads are built, therefore, the heavier and 
the faster may loads be moved over them. If the road- 
bed rises ofte foot in 100 feet it is said to have a one 
per cent, grade, and this anionnt of slope will increase the 
draft one ]>er cent, of the weight of tlu^ load over what it 
would be on the same road-bed level. A two per cent, grade 
rises two feet in every 100 feet and the draft is increased 
by it two per cent, of the load ; a ten per cent, grade rises 
ten feet in every 100 fe(4 and will increase the draft of a 
ton 200 lbs. over what it is on a level road of the same char- 
acter. The heavier the loads to be moved, then^fore, the 



429 



more ohjcctioiiiihic bccoiiics any .<i;i'}i<l<' iivtlic I'oaH. Tlias 
is wliy with all raili'oadrt the heavier their freif»lit the more; 
they overhaul their tracks and lower the ^rade. 




Fid. 20ft.— Appjinitiis for ticiiKiiislrsitiiii: the iiittiiciife of difTcicMr ^'r:l(lt's 
nnd of obstructions on f\u; draft of wayonH or roads. 



530. Experimental Demonstration of Influence of Grade on 
Draft. — III Fi<r. 209 tlio .steel har may he .set so that it 
represc^iits any ^rade from one to twenty per cent., and 
by sotting the road \}('(\ at these different grach'S the spring 
balance shows tlu; force necessary to sustain the load in 
the several cases. If the load with the carriage is made 
equal to 00 lbs. then the .scales will read .6, 1.2, 1.8, 2.4, 
etc., up to J 2 Ihs. for the 20 per cent, grade If now the 



430 

road Led is set for a 10 per cent, grade and then the load, 
including the carriage, varied it will he found tbat the 
draft on the scale will be always 10 ])er cent, of the load. 

531. The Mechanical Principle Involved in the Relation of 
Draft to Grade. — It is a general truth or principle in over- 
coming anv resistance or in doing work of any kind that 
the force or power doing the work, when multiplied by the 
distance through Avhieh it moves, is always equal to the re- 
sistance or work multi])li(Ml by the distance through which 
it is moved. Stated mathematically the equation stands 

Power X Power Distance = Weight > Weight Distance 



P. X P- D- = W. < W. D. 

Suppose the road-bed in Fig. 209 has a lengtli of 100 
and the grade is 10 per cent., then if a load of 60 is drawn 
along the length of the road the power will lun-e passed 
over a distance of 100, acting parallel with the road bed, 
but, leaving friction out of consideration, the Avork done is 
to lift the load vertically through a distance of only 10, 
and since the distance which the weight is raised is only 
A of that over which the power has acted it is only neces- 
sary that the pttwer shall be "/» of the weight or 

P. X P. D. = W. X W. D. 

P. X 100 = 60 X 10 
whence 100 P. = 600 
and Power = 6 lbs. 

532. The Steepest Grade Admissible. — When it is asked 
what is the steep)est grade which should be permitted on a 
given road there are many factors which must Ix; consid- 
ered, but the most general rule is to make the grade as small 
as practicabki on roads where horses are expected to carry 
all they can well handle on good, nearly level roads, and 



431 

the better the level ])art of the r(»a(l, the longer the haul 
and the more teams to ])ass over it, the less steep should the 
grade he. On all well designed roads a great effort is 
usnally made to keej) l)el()\v a rise of seven feet in 100 feet. 

Just M'hy low grades are so necessary will he readily 
understood from the following considerations: 

About the maxinnim walking draft of a horse on a good 
level road is measured hy onedialf his weight. Trials have 
shown that a l,(i.'>ldb. horse can excn't a steady pull of 
800 lbs. Avhile walking 100 feet, and that an 83G-lb. horse 
may maintain through the same distance a steady draft of 
400 lbs. It would not be safe, however, to repeat such 
strains often nor maintain them long. Even a draft equal 
to oue-fourth the Aveight of the animal is a heavy and ex- 
haustive pull. Indeed a steady pull eipud to one-tenth of 
the. weight of the horse for a tendiour daily service at the 
Avalking pace of 2.5 miles per hour is an average of effect- 
ive service and the work of a l,0'00-]iouud horse Avould 
equal 

5,280X2.5X100 _ . h P 
60X33,000 => "• ^ 

Taking this as the safe rate of work for a team on the 
road an 800-pound horse may pull steadily 80 lbs. ; he may 
pull over hills at the rate of 200 lbs. and in emergencies 
400 lbs. A l,600-})ound horse at the same rating may 
pull steadilv ir)0 lbs., up hills 400 lbs. and in an emeTgency 
800 lbs. 

It has been found that to move a gross ton over a good 
level dirt road requires a traction of about 140 lbs. A 
team of 800-pound horses may therefore come to a hill with 
a load of 

.j-tt; tons = 2,2855 pounds. 
140 

Up how steep a grade may such a team carry this load 
with a steady exertion of 200 lbs. jier horse? To over- 



432 

come the resistance the road bed offers to the h^ad requires 
a steady pull of 

and this leaves the reserve draft to go np the grade 
(200 :■: 2) —160 = 210 

The load to he carried up the grade is the weight of the 
team plus that of the load or 

(800 v; 2) + 2,2855 = 3,885f lbs. 

Up how steep a grade will 240 lbs. carry 3,885f lbs.? 
Solving this problem by applying the principle of (531) 
we shall have 

P. X P. D. ^-- W. W. D. 
or 240 X 100 -= 3, 885f X W. D. 

, „- „ 24,000 „_,. 

whence W. I). = = b.lib or 

o, oo52 

a rise of about 6.2 feet per 100 feet, which is a 6.2 per cent, 
grade. 

By taxing the team to its utmost capacity its effective 
power to ascend, the grade would be 

(400 X 2) — 160 = 640 lbs. 
Proceeding as in the other case we shall have 

P. X P. D- = W. X W. D. 

and 640 X 100 = 3,885? x W. D. 

6,4000 _ .^ 
whence W. D. = = 16.4 < 

O, OoOS 

or about a 16.5 per cent, grade. That is, a grade of 16.5 
feet in 100 feet is the steepest dirt road a team can be ex- 



433 

pected to carry tlio load over wliicli it was able to briug 
over a level dirt road to it. 

These results have been computed from the standpoint 
of an SOO-jxiund horse, but since the ability of a team to 
work is in a general way proportional to its weight the 
same results would have obtained had we taken the 1,600- 
pound horse with a proportional load. 

533. Good Roads Make High Grades More Objectionable. — 
When the good macadam road bed is substituted for the 
common dirt road then the same draft, 140 pounds, which 
draws a ton on the dirt road will draw 

140 

-^ = 2^ t\mes as much or 4,666| lbs. = 2^ tons. 

on the level macadam road. Since it requires but 60 lbs. 
to move a ton on a macadam road it will require 

60 ;<; 21 = 140 lbs. 

to draM' the 2-t tons on the level road, hence the effective 
power of the team will be 

4(X) — 140 = 260 lbs. 

Up how steep a grade will 2(>0 ll)s. carry the team and 
21/^ tons ( Solving this as we did the other we get 

260 X 100 = 6,266| X W. D. 

, .„ ^ 26,000 , ,,„ 

whence W. D. = _ ' „ = 4.149 
b, 2od| 

or a little more than a 4 per cent, grade. That is to say, 
when a dirt road is improved so as to reduce the draft from 
140 lbs. per ton to 60 lbs. per ton then, in order to utilize 
this improved road with equal effectiveness under the con- 
ditions assumed, the 6.2 per cent, grade should be reduced 
to 4 per cent. ; and the highest grade could not exceed 
10.53 }>er cent. 



434 



DKAFT or UA'ioXS OX THE LEVEL. 

There are many factors Avliich modify the draft of a 
wagon over a h'vel road and some of the most important oi 
these are: 

1. Smoothness of the road-bed. 

2. Rigiditv of the road-bed. 

3. Width of the tire. 

4. Diameter of the wheel. 

5. Dis'tribntion of the h)ad on the carriaiic 

6. Direction of the line of draft. 

7. ]\ig'idity ot' the t-arviaiic 

534. The Smoothness of the Road-bed. — "When the road- 
bed is not smooth and has nnmerons I'nts, stones or other 
obstructions npon its surface, the draft of the h>ad is in- 
creased and the wear on the vehicle and on the road-bed 
is also greater so that much effort and care shoidil bi- ex- 
ercised to have the road smooth. The increase iu the 
mean draft of the load is not so great, howt'ver, as rlu' other 
dilficulties which result for the reason that when the wheel 
enters a rut or passes down off from an obstruction there 
is a push forward which tt'nds always to give back a ))ortion 
of the energy ex}>ended in I'aisiug the load upon the ol)- 
struction or out of the rut. 

535. Rigidity of the Road-bed. — A yielding road-bed is 
perha})s the most serious defect of roads, and the one which 
inci^eases the draft more than any other. If a wheel is 
steadily cutting into its road-bed it is continmdly tending 
to rise over an obstruction ov out of a rut. or it is doing 
what is in effect all the time passing up a grade, as repre- 
sented in Fig. 210, the hill being steeper in proportion as 
the wheels are smaller. 

In Fig. 200 is represented a method of measuring the in- 
crease in draft due to the wheel rising over an obstruction 
whose hight is a stated ytov cent, of tlu' radius of the wheel. 



The arraiiii'eniPiit at (' is provided witli a screw and iii-adn- 
ated so that tlio hl<»ek may l)e raised or lowered al will, 
setting it so as to re pi-esciit rlie wiiecl passinu' (>\-er an oh- 
struction, 3, 4, 5, etc., per cent, of the i-adius (»f the wheel. 
By setting- the road-hed indiiKMl ;is shown in the tignre, the 
draft is first noted and then the thumh sercnv at 1) is turned 
until the wlund rises upon the hloek and the diffei'ence be- 
tween the two j-eadings of the scale exjjresses the increased 
draft due to the ohsri-uctioii. 




When the ohstrnetion is oidy four [lei- cent, of the radius 
of the wheel the di-aft is increased inore than two-fold. 
That is to say, if a wheel is 4S inches in dianietei'. an ob- 
struction of four ])er cent, would lie oidy .IXi of an inch, 
and yet the draft is nuide by it more than twice as heavy. 

When the wheel cuts in one inch the draft would not in- 
crease quite so much becaust' the wheel never rises quite 
out of the rut, but the diiference between the draft on the 
macadam and dii-t road is diu^ nu)stly to the ditference in 
the yielding, oi* cu.tting in of the wheels. 

An experiment conducted by the I'nited States Depart- 
ment of Agriculture, testing the draft of ordinary wagons 
on a steel wagon road, showed that a single small horse 



436 

oiiHily drew 11 tons, <>v ii2 (iiiicH ilic- woiglit of the animal, 
and it is Htutcd in tlu^ report tliat tlic lioi'Bo could readily 
liii\'(' lianlcd r»0 times his own weight. Tliis would he, for a 
|,()()0-p(innd liovse, LT) tons, hnt ol' course wilh such a. h>ad 
thi(^ i'o;id nuisl h(< pr;icl i<';dlv h'Vel, tor :i <;r;i(le (d one per 
cent, woidd increase ils(h';ill r>(»0 pounds. 

536. Draft of Wagon Shown by English Trials. — The 
powi^r re(|iiire(| lo draw ;i Innr wliee|e(| \\';ijL;on oNcr roads 
of ditl'erent chai'aclers has l)een lesled :ind ihe tullowing 
(!X|)i'esses the results in. poun<ls per :J,000 Ihs. of ;i,ross load: 

On cubical block pavmiuMit 28 to 44 IbH. per ton 

On niiicadain roail 55 to (i? ll)s. [km* ton 

On t4ravt^l road 75 to 140 lbs. pt^r ton 

On plank road 25 to 44 Ib.s. par ton 

On coMinKin dirt road 75 to 224 ll).s. per ton 

537. Draft With Different Widths of Tire.— Prof. .1. JI. 

Waters' has made an exiended series (d' I rials to tesi the 
effect of the widi li <d' I ires on Hie dra 11 id' loads under dif- 
foroit conditions <d road. IN' used always a net load <d 
ou(^ ton, hut the (1-ineli lire(| waj^ou was li-ff) pounds heavier 
than the l.."! iiu-li, makin;;' ihe ii,ross loads '.},"2)1^» and 'J,!>SO 
j)ounds respecl ively, when the wa:;(iiis were tree from mud. 
'r\w following' are his residts: 

On niai-adani Htrents, wide tire 2G per cent, less than narrow tire. 

On gravel road, wide tire 24.1 per cent, les.s than narrow tire. 

On (iirt roaiJH, dry, smooth, free from dust, wide tire 26.8 per cent, 
less tiian narrow tire 

On clay road, with nuid deep, and drying on topand spongy ixmeath, 
wide tire 52 to (il per ct^nt. less than narrow tire. 

On meatlow, pastin(\ Htul)ljle, corn ground and f)lowed ground 
from dry to wet, wide tire 17 to 120 p(fr cent, less than narrow tire. 

On ihe oIImi- liaud hi' touud that when the roads were 
eoveretl wilh a deep dusi, i>v wilh a Ihin mud Iml hard he- 
low, the narrow I i red wa^on ga\'e the liiihiesi dratl. .\lso 
when ihe mud was lliick and so slicky as to roll up on ihe 
vvhe<'l, loading' it down, ami a^ain when narrow tired 
wagons had made dee|> ruts in the road which the wide 



> Bull. No. ;{'J, Missouri Agr. K.xp. Station. 



43T 



tired wagon tended to fill up, tlic narrow wheeled wagon 
gave the lightest draft. 

538. Size of the Carriage Wheel, — It is plain from what 
lias been said, that on yielding road-beds the draft must 
necessarily be heavier, other things being the same, the 
smaller the wheels of the vehicle. This must be so both 
because small Avheels present less surface to the road-bed 
to sustain the load, and because when the wheel has de- 
pressed the surface it must move its load up a steeper grade 
than the large wheel. It follows also from these state- 
nnnits that wagons with small wheels must be more de- 
structive to the road itself, whether this be of dirt, gravel,, 
stone or iron. 

Some unpublished data bearing upon this point are given 
here by permission of Prof. T. J. Mairs of the Agr. Exp. 
Station, Colnnd)ia, ^lo. 

Wagons with three sizes of wheels were used in these 
experiments : 

1. High, 44 inch front wheels and 56 inch hind wheels. 

2. Medium. 36 inch front wheels and 40 inch hind wheels. 

,3. Low, 24 inch front wheels and 28 inch hind wheels, all having 
tires 6 inches wide. 

The total load including the wagon was: For 1, 3,762 ; 
for 2, 3,580, and for 3," 3,362 pounds. 

The drafts in his trials are stated in the table below : 



Description of Conditions. 



Dry gravel road: sand 1 inch deep; some small, 
loose stones 

Gravel road up grade 1 in 44; covered with one-half 
inch wet sand ; frozen beneath 

Dirt road frozen; thavping oue-half inch; rather 
rougli ; mud sticky 

Timothy and blue grass sod, dry, grass cut 

Timothy and blue grass sod, wet and spongy. .. — 
Cornfield, flat culture, with spring-tooth cultiva- 
tor ; across rows ; dry on top 

Plowed ground not harrowed, dry and cloddy 

27 



High 
wheels. 


Medium 
wheels. 


Lbs per 
ton. 


Lbs. per 
ton. 


84.48 


90.45 


123.0 


132.1 


100.6 


119 2 


131.9 


145 2 


172.9 


202 6 


178.5 


201.2 


252.5 


302.8 



Low 

wheels. 

Lbs. per 
ton. 

110.2 
173.1 
139.1 

178.8 
281.1 
265.1 
373.6 



438 



For uso on the I'ariii the advaiitiiiic^ of truck or low wheels 
comes in the saving' of lal)or in liiiili lifts in placing 
manure and other materials upon tlu^ wagcm, and here a 
sacrifiee of strength of the horse may advantageously be 
made to save that of the man. A lighter draft and lower 
life in handling loads are seeiire(| by nsing the low (h)wn 
carriage hed in the nppei- part of Fig. 211, than are possi- 
ble with the \'ery low whe( led wagons shown in the same 
ent. 

539. Distribution of Load on the Carriage. — When there 
is nothing to prevent doing so, the load carried l)y the 
wagon should he so (listribnte(l npon the wheels as to be di- 
vided ])ro))ortionately to the surface the wdiecds present to 
the ground, and when the front wheels are' smaller they 
should carrv a snuiller load. When care is not exercised 




Fi<!. 211. 



in this matter there is danger, especially on soft roads and 
in the field generally, <d' very materially increasing the 
labor of hauling. When the load is heaviest on one side 
the wheels of that side are unduly deju'essed, thus increas- 
inffthe draft, 'idie tilting (d the wagon in this wav throws 



439 



tlie ceiitor of the load to one side still furtlier and to a 
very serious degree if the load is high, as is the case in 
hauling hay or eord-wood. 

540. Heaviest Load on the Hind Wheels. — In loading the 
ordinarv Avagon the heaviest load should l)e ])hu'ed on the 
hind wheels for three important reasons: First, because 
they are larger and will not de})ress the road-hed so much 
and will draw easier if they do; second, when the wheels 
track, the front wheels make a road, by tirming the ground, 
over which the balance of the load may be more easily 
drawn; third, when the axle of the front wheel is free to 
be turned, as in tlie common wagon, the slight inequalities 
of the road-bed tend all the. time to keep the tongue vibrat- 
ing, so that there is a strong tendency, by this to and fro 
swinging, to cau-<e the front wheels to cut more deeply into 
the ground and thus increase the draft. On a very rigid 
roadd)ed this matter is not as important as in doing field 
work, but the diiferences are large enough on earth roads 
so that they should never be overlooked. 

In the following table some obs(M"ved (lifl'ei'(M)C('s are re- 
corded : 





Dry sheep 
pasture. 


Dry 
meadow. 


Load equally on four wheels 


Lbs. per ton. 

110.4 
120 
l':;9.3 
101 8 


Lbs. per ton. 
171 




187 5 


Load heaviest oil front wheels 

Load heaviest on h iud wheels 


2i9.9 
190 9 







These statements may ap])ear to contradict the common 
practice ot hauling higs hutt end forward and the general 
tendency of ])lacing the heaviest portion of the load for- 
ward. The conditions, however, are quite dilferent from 
those where there is a real advantage in placing the heav- 
iest load forward. The reason for this will be better un- 
derstood from the c(!nsid(>rations of the next paragraph. 



440 

541. Direction of the Line of Draft. — lu drawing a load 
over a plane surface which remains unchanged during the 
movement the least draft is required when the line of draft 
is maintained parallel with the road as shown at A. B., 
Fig. 212, wiiere the apparatus may be used to clearly dem- 
onstrate this princi])le. It will he seen that as the spring 
balance is moved u}) upon its arc the line of draft is such 
that it tends partly to lift the load oif the road and so 
much that if it were pushed around until the direction 




Fig. 2l2.^A!H)ar;itn>i fur demonstratins the influence of the direction o£ 
tlie line ot draff iin tlie draft nf wagons. 

became vertical the whole weight of the load would come 
upon the spring balance. Then, too, if the line of draft 
is carried below a parallel to the road-bed the draft must 
increase because then it is partly do\vnward wpon the bed, 
tending to practically increase the weight of the load by 
the lost portion of the force of traction, for it is clear that 
were the scales carried downward until the draft became 
vertical to the road the Mdiole effect would be lost in pro- 
ducing pressure. 

In the movement of cars by the locomotive over the 



441 



smooth nil vicl'liiiii '»<'<! of" tlic steel mil the line oi di'aft 
is always parallel with the rail. 

542. Line of Draft on Eoad Wagon. — The statements of 
tliG last })arai>,raplL may appear to be contradieled by the 
general practice of having the traces nearly always slope 
decidedly backward and downwai'd. The former state- 
ments, liowever, are not incorrect, neither is the common 
practice fnndamentally wrong. The apparent contradic- 
tion grows ont of the fact that the road is seldom either 
smooth or rigid so that the wheels on the average are in 
effect continnally rolling up an inclined plane. 

The principle is clearly shown in Fig. 213 where the 
wheel is rising over the obstruction which in effect makes 




Fi<;. 21S. — Apjii'r.it IIS fm- dcnioiistriitiiiji the iiifliK'Ucc, iiixiii the draft, of 
the rtirertioii (if the line cf the draft nf ;i wafioii when the wheels ;ire 
passing' over an ohstrnctiou or cuttiiifi into the road or jji-onnd. 

an inclined road upon the general road-bed. If now 
the draft required to bring this load upon the obstruc- 
tion is measured when the line of draft is parallel with 
the general road-bed and then the line of draft is made 
more and more slanting until the direction finally be- 
comes parallel with the secondary road made by the ob- 



442 

stnietioii, it Avill be found that tlie draft dt-creases until 
this direction is reached, but that passing beyond it again 
increases. In other M'ords, the draft is least when the di- 
rection of tlie traces is parallel with the effective road-bed. 

It is clear, tlierefore, that in teaming with wagons on 
the Held and on any but rigid, smooth roads the least draft 
is secured when th(> traces incline more or less downward, 
the amonnt increasing the more yielding and the more un- 
even the road. 

In regard to the di\'ision of the load between the front 
and hind wheels it is clear that the hind wheels are drawn 
bj the reach from the king-l);dt, the line of draft being 
nearly horizontal, and, this being true, it may fairly be 
concluded that on ordinai-y roads and upon the Held the 
load must draw harder if the heaviest portion is not placed 
upon the front wheels where the line of draft can be more 
inclined. It is quite possible and even probable that when 
the unevenness of the road is considerable the least draft 
may be secured when the front wheels are carrying more 
than half the load. More observations, however, are re- 
quired along this line to establish the whole truth. 

543. Rigidity of the Carriage. — Where the road is notper- 

fectly smooth and where the speed is faster than a medium 
walk, springs under the load diminish the draft and the ad- 
vantage of elasticity increases with the roughness of the 
road and with the speed. For small and rigid inequalities 
in the road the maximum advantage is secured in the use 
of the elastic tire, and especially with the pneumatic form, 
where the load is not too heavy, because in these cases 
the energy which would be lost by concussion is prevented, 
the tire quickly and effectually conforming to the road. 
Where the loads must be heavy, and where the inequalities 
are larger, then springs under the load carried by the axles 
respond in rapid transit and relieve the concussions and 
thus lessen the draft, diminisb the strain upon the car- 
riage, and permit less injury to the road. 



443 

544. Results of General Morin's Experiments in France 

General JMorin. after a series of experiments carried on 
nnder the French government, reached the following- con- 
clnsions regarding the draft of carriages on roads: 

1. The traction is directlv proportional to the load, and 
inversely ])roj)ortional to the diameter of the wheel. 

'2. I ])oii ])aved or hard macadam roads the traction is 
independent of the width of the tire when this exceeds 
three or fonr inclies. 

.';. At a walking pace tlu^ ti-action is the same for car- 
riages with springs as for those withont springs. 

4. rpon a macadam or paved road the traction increases 
Avitli the s])eed ahove a velocity of 2.25 miles ])er honr. 

5. Upon soft roads of earth or sand the traction is inde- 
pendent of the velocity. 

6. The destrnction of the road is in all cases greater 
as the diameter of the wheels is less, and it is greater by 
the nse of carriages withont springs than of carriages with 
them. 



444 



CHAPTER XXI. 

CONSTRUCTION AND MAINTENANCE OF COUNTRY 
ROADS. 

Having outlined the principles underlying- the draft of 
wagons on roads the next consideration should be how to 
make and maintain the road for the given locality which, 
everything considered, is the most economical. 

545. Establishing the Grade. — For ordinary country 
roads the road-])ed will generally conform with the natural 
slope of the surface over which it passes ; steep hills, how- 
ever, should, if possible, always be avoided either by turn- 
ing to one side or by grading and filling. 

Where the hills are short and steep they may usually be 
graded down to better advantage than to pass an mud them, 
but when the hill is both long and high then it may be best 
to reduce the grade by j)assing obliquely up the hill, or in 
mountainous countries where ranges are crossed through 
I^asses it often becomes necessary to pass down the long 
steep slopes by a series of zigzags, having short and steep 
rounded turns. 

546. Factors to Be Considered in Establishing the Grade. — 

There are many factors which must be considered in de- 
ciding the particular grade a road over a given hill may 
be permitted to have. If the road for the main travel is 
generally excellent and level, with a good deal of traffic 
over it, then it is important to keep the grade as low as 
practicable. Where the country is generally rolling, so 
that there are many hills which must in any event have 
a high gi-ade, it will not be as important to cut other hills 
down as much as a more level country would warrant. 



445 

The better the more level portions of the i'<»a(l are, where 
heavy teaming is done, the more important it i« to reduce 
the grade to a low per cent, because it is important to be 
able to go over any hill readily wliicli can In^ ap])i'oached 
with the largest hiad the team is able to handle without in- 
jury to itself. The great importance of this point will be 
readily understood when it is stated that the steepest grade 
admissible on an average macadam roa<l is 10.5 per cent., 
and on a dirt road in good condition 10 per cent. But 
as these grades will tax the team to its utmost the hills 
should not be jjermitted to rise if practicable faster than 
4 feet in 100' feet for the ordinary macadam and 0.2 feet 
in 100 feet for the earth road in good condition. 

In thinly settled sections ])eo]de must be content to im- 
prove the roads gradually, but if the end iinally to be 
reached is kept in mind all the time it will usually be pos- 
sible to make each year's work count as pernument im- 
provement and avoid tearing down one year the work of 
the years preceding. 



EOAD DRAINAGE. 

The kee])ing of the road dry, both above and below, is 
the most fundamental necessity of a good permanent high- 
w^ay. Fill any soil, however hard and firm, completely 
with "vvater, and a child walking over it will mire ; and to 
completely drain and dry any soft and marshy place will 
leave it so that heavy loads may be moved across it readily 
and safely. Drainage is one of the first requisites of a 
good road. 

In some places only surface drainage requires attention. 
Where the surface is more or less rolling and underlaid 
with coarse porous materials, so that standing water in 
the ground does not occur within 10 to 20 feet of the sur- 
face, under drainage will not ])e necessary; but wherever 
the adjacent fields would be improved by drainage, wher- 
ever the ground is springy, and wherever the ground wa- 



446 

tcr at auv scasdii ol the yv.w rises to within three ov four 
feet of the siirfact tiiere tlie I'oad-hed slioiihl he draiiUMh 

In Ininiid eliiiiales provisions shoithl he iiuuh' to surface 
lira in everv i-oatL 

547. The Relation of Water to Roads. — AVheu a soil it; 
eoni]>h'tel\ li Hed with water the iiulividual soil gTains are 
iuvestiHl hv wati r and tend to float in it so that there is the 
ii'reatest freedom of motion of the jKirtieles. On the other 
liaiid h't all water he removed troni the soil and the j:,round, 
whih' hard. I'asilv frets into tini-, loosi', si'jiarate dust 
partieles, which not only increase the draft hut ai'e easily 
drifted away hy the wind, thu> injnrini:- the road much 
as it would he were llie top waslunl away hy running 
water. 

There is a meilium condition or amount of water in the 
soil which gives it pt)wer to withstand the eroding tendency 
<»f the tramp of the horses' feet and the rolling of thi' 
wheels. When sand is just wet enough its surface is hard 
and will carry a hea\y load, th.e grains heing hound tii- 
gether hy tln' surface ti'usion <,»f the water films. So, too, 
with the clay roads and th;ise of the host of loam, tln' right 
amount of water always ju'csent, so as to keep the sur- 
face dam]) and dark without making them soft, greatly 
improves the ipuility and lengthens their lite. So \alua- 
ble is the right amoiuit of watt'r on earth roads thai spi'ink- 
ling tlu'iu in arid and semi-arid (dinuites and in di-y times 
in liumid clinuitcs. is one (d' the most t'tlectixc means ot 
uniintenauce. 

548. Depth of Under Drainage. — AVherc under drainage is 
n{H>ded the drain shoidd not he less than three t(» four feet 
deep, and this is I'specially true if heavy trathc is to ho 
maintained over it. 

No one thiid\s of walking on th(> yielding surface of the 
water of a lake t)r stream, hut let it lie coveri'd with a sutfi- 
ciently thick layer of ice ami it then makes the host kind of 
a road-bed. The drained iiroiind heneath the road surface 



447 

Jiitist lie siiHi<'i(iitlv tliick i<> riii;it. <ni the soft s(»il hfiiciitli, 
any lojid wliicli iii;iv h:- di-ixcii almifi' it, jiisl hs llic ice Hoats 
its hiirflcii. 

549. Place For the Drain. In the narrow roads of eight 
to sixteen feet, wlici'c tlic water to he removed is tliat which 
may lie raiseil !»y hydrostatic ])ressure verticall\- upward 
beneath the r<iad-h('(h the hest ))]ace for the di'ain is di- 
rectly heiicath the ('(liter <il' the drive-wav. 

Where tlie main snni'ce of the water cansin'i' the trouble 
is an underilow thi'oui;ii sands and i;rav(ds fi-om adjacent 
hi<ilier hinds then the di'ain sliouhl he phieed upon the side 
of the road from whicli the water comes. 

Where the ground is marsliy on all sides, and ])artic\i- 
larly if tlie i-oad is wi(k', it may tlieii h(< necessary tO' lay 
two lines of tile, one on each si(h'. 

If spriniiy phiccs occur iiiuh-r (•]■ near the road-bed 
drains must he connected with the spring itself, so as to 
effectually i-emove the excess of water. 

550. Fall of the Drain. — The fall of the drain Avill nsU'- 
ally conform somewhat nearly to the grade of the road-bed, 
but should not be less than two inches in 100 feet, if this 
can be secured. It will, however, be necessary sometimes to 
lay the drain on a slope less than this, even, as low as ^ 
an inch in 100 feet. In all cases care should be exercised 
to lay the tile on a ti'iie gi-ade, not allowing them to drop 
anywh(M-e helow or rise ahove a rigidly maintained grade 
line. Jf they are not laid in this manner water will 
stand in the sags and behind the hends, and in th(^se places 
the tile may become filled with silt. 

It may sometimes (jccur that the road is .so nearly level 
that there is no fall for the drain. In such cases it may 
be necessary to lay the Ijeginning end of the drain nearer 
the surface of the ground hy as much as six or even twelve 
inches. In this way there could be given a fall of one inch 
in TOO feet over a distance of 1.200 feet, but of C(3urse 



448 

the ii|t|M'r |i(irlii>!i <<!" llic ncid coiiM not he ;is well drjiiiKMl 
uiul the pliiii slnmld lie rnllowcd diilv wlici-c llicrc is no 
other iiltcniiilivc. 

551. Outlet of the Drain. — The drjiiii should bo turnod 
out to tlio si(h' of the I'oad wliouovcr Ihci'c is uu opportunity 
for doiuii,' so, that is, whcvucvcr there is a uatural lino of 
draiiiai;(' hadiiii;' aei'oss tlie road which will answer for the 
j»ur|)ose. riie free end of the drain is best uia<l(^ of one 
]eni;tli of cast iron sewer pipe ei<;'ht fe(^t loui>', because; this 
M'ill not be injured bv i'reezini;' uor b(^ easily broken. There 
should be a I'va' fall at the end of the drain, and it is better 
that the openiiii; shouhl be protected bv some sort of metal 
g'ratini;' or screen to pi'e\'eiil aninnds from running' in in 
drv t imcs. 

552. Size of Tile. Tile thi'ce inches in diauu'tcr is the 
bi'st to use lor the reason that, in case the i;ra<le is V(!ry 
snudl, slight errors in laving the line cainiot, carrv the en- 
tire opening of the tile above or below the grade line and 
lieiice permit the drain to be enlirelv closed bv sill. 

553. Kind of Tile. — Where the tile can be laid two feet 
or more below the surface of the I'oad oi'dinarv di'aiii tilo 
which are well bnrned, straight, smooth inside and having 
the ends cut s(puirelv olf so that thev nuiv lit closely to- 
gether are best. (ireat cai'e should be taken in placing tliQ 
tile to tniai them until the en<ls lit \crv closelv all the way 
around, and then to li\ them rigidl\' there. This care it^ 
needed in order to pi-e\'ent silt. I'rom being washed in at 
the joints. 

Whei'c the tile must come less than two feet below tin; 
fiurface il will be safei- either to use the \itrilie(l drain tile 
or (dse second (pndity sewei- lile not likely to be disinte- 
gratiMl bv frost. 

554. Surface Drainage. — Tlie quick removal of water 
from the surface of a I'oad and the prevention of seepage 



440 

<]()\vii tlirouiili the road-he*! arc; tint most, iniporlaiit points to 
be seemed in the niatler of iiuiiiitcnance. The surface of 
everv road, tlierefore, ^lionld lie so shaped as to act like 
a ro<d' ill ihi'iiwii!^ all rains (piieklv and eonipletely off, 
perniitt ini;' onlv a little moist ni'e to lie drawn downward by 
capillai'v attraction to moisten the matei'ial and lessen 
the t'oi-mation of dnst. if the eonipaet('(| material <>\' the 
road and the I'oaihhed hcneath it can he kej)t with only a 
small i>ei- cent, of eapillarv water in them the danjifr of 
irijni-y lieni frost is i:i-eat!y lesscne(l and the liahility to 
soften dnrinii,' wet pei-iods is idsu lamely removed. 

Water shonhl under no conditions he permitted to stand 
either upon the surface nor alonj;' the side of the; I'oad, the 
Kha|)e heiiiii' snthciently i"(ninde(| to thi'ow the rains cpiickly 
to either side, and the snrfa<'e dit.ches deep eiioniih, clean 
enon^h and possessina snllicient ciipacity to cai-ry id; water 
rapidly away. 

555. Slope of the Road Surface. — In order to luive quick, 
comj)lete surface drainage it is uecessary to so ai'ch the 
face, as to make a road twelve feet wide thi-ee inches hiyher 
in the center than at eithei' mai'iiin, a slope of ahont four 
per cent, or foiii- inches in 100 inches. Dnt if the road 
has itself a considerahle j^rade, then the slo])e must be 
made (nuiu^h greater than four per cent, to force the water 
to the side ditches i-ather than to permit it to How down 
the center of tiie road. ihif (^'(jnness or smoothness of 
surface is the most im|<ortant Cf)ndition to he secured and 
maintained in order to afford })erfect di-aina^e. If the 
road surface is left uneven, or is ])ermitted to hecome so, 
no amount of slojje which can he tolerated will secure the 
draiiutiic. 

The. road must imt he nnide too )-oniidin<;' or sloping' for 
the reason that then teams all drive in one place on the 
surface and wear it into ruts and this pre\'ents draina^:e. 

556. Water-Breaks. — On steep grades where the liill is 
long it is a common practice to throw a ridge (jhli(piely 



450 



across the road ,\t iiiti'rvals to tiini the watci- to llic sidt^. 
Tills is a had praclicc and slidiild he axoidcd wlicrcvor 
possible, and in all hut the steepest i^rades this iiiav he done 
})V iiiakinii' the slope of tlie I'oad hi,<i!ier than the j'^rade. 

It' the watei- cannot he liirne(l nil' in this way it is het- 
ter to make two pave(l <^iittei-s meet in li \'-siiape(l in tlie cen- 
ter of the road with I he point np t he iira(h'. Tlie |)aviii<;' will 
prevent washing;' and niakiiiii' the fitters meet in the cen- 
ter does not lip the waii'on in passini> across them. 

\\'liene\'er it hecdines necessary to cari'\' water across 
a road on a hill from one i^nttei' to the other it is mneh 
better to cai'ry it nnder the road than ahoxc it, as is so 
often done with the aid ol waterdtreaks. A cnKcrt is of 
course necessai'X' bnt it shonld he \\>('d. 



'I'K.XrrU'K <)K IJOAI) AlATKUIAl-S. 

Closeness of texture is necessary to the building' of a 
solid road, 'i'lie more complet(dy all ])ores can be obliter- 
ated ami the road iii\-en the close texture (d' iron the bettei- 
and more dnrable will it l)e. 

Fi(dd soil in its natnral con<lilioii may ha\-e from .'<() 
to 50 ])er cent, of space unoccupied by anythiu'j, bnl water 
and air, and in this condition it cannot form a uood roa<l. 
It is too yieldiuii' to jiressni-e and water ])ercolates ihroniih 
it too rapidlv. W'lieij it is pi-operly rolled ami tamped 
the pore s|)ace is xcry greatly i'e(lncei|, iii\ing it so (dose 
a texture that watei- does not enter it readily, and so large 
a portion (tf the grains ai-e in actual contact tha.t it ap- 
proaches the character of a rock. Of whatever material a 
road is built it should jx-i'init the parts to pack so (dosely as 
to reseudde a solid rock. 

557. Roads Should Be Built in Layers. — Whether a road 
is to be built of crushed I'ock or earth it is indispensable 
that the mat(M-ials used shall be put on in layers. The 
thickness of the layers will depend primarily upon tho 



i:. I 

si/c of the ])ic('cs of iiwitcriiil nsc(|, the hivciv^ IxMiii;' thicker 
the coarser the iii;itcri;il. With crushed r«x*k having 
pieces 2 to 2 1-2 inches in dijiiiietei' the hiyers will need to 
he .'i to I inches thick ; with smaller pieces the hivei's sliould 
be thinner. If tiiicker la vers than these ai'c made tiie ef- 
fect will he the formation of a (dosely packcfl crust, a lit- 
tle thicker than the dianieler of the niiitcrial nse(l, over a 
loose and o[ten structure ludow. 

The hai'<lest an<l hest eartli I'oail can he huilt onl\- hy 
si)readin^' the matei'ial on vei-y unif<»i'ndy in thin layei's 
and thoi'ouiihly compactini>' each layer hcdore th<' next is 
l)Ut in plaec ; the thickness of these iayei's should he 2 
ijiches ami less, rather than more. 

558. Uniformity of Size of Material Used. — It is impossi- 

hle to ci'ush r<!ck into si/es \aryini: all the way fi'om fine 
dust to ])ieces \.'t inches in diameter and then use this ma- 
terial unsoi'ted to make a solid, unyi(ddin<i' road. The 
inatf-rials wlien laid down at once with all sizes mixeil will 
not pack so as not to work up loose with the t ravel u pon it ; 
and this is the main i-easou why more soli(l roaijs cannot 
he huilt from earth. 

('rushed rock must he cai'cfully se])arated into nearly 
uniform si/es \)y means of sci'ceiis and the diflereni iira<les 
ap])lied to the road in hiNci's. 

Wlien a layei* is made of oidy a sinjile size of pieces 
these may he l)roUiiht toiicther hy packini:' so tliiit all toucli 
and pr<'ss firndy aiiainst one another. If now a urade is 
used of smaller pieecs su(di as will woi-k readily into the 
poi-es left between the anaies of the iariicr ones, pi'cssin^ 
hard u])on all sides, a still more stable layer will be formed. 
If it were practicable to follow this method step by step 
there woidd be repi'oduee(| ;i iiearl\' solid rock troni the 
fraiiUients made and the most substantial of roads built. 

559. Shape of Fragments. — 'Ihc slia|)e of the nmterials 
used in I'oad building lias iin|)ortant Ix'arings on the (piality 
of the road. The best form is that wliich ap|)roaches most 



452 

closelv to the t-uliv with Ijiviad. Hat faces, sharp angles and 
having the same diameter in thi-ee dircH'tions. Fragments 
of this form pack most readily and, as the broad, Hat faces 
set against each otlier, the fragments do not so readily turn 
nnder the wheel or horses' feet and withstand a heavier 
load without crushing. 

Where sands and gravels are used in road l)uilding those 
of glacial origin which are mncli sharper and more angular 
than water worn types are much to be ])referred, for the 
simph' reas(Ui that when packed together they give a more 
rigid body and stronger binding. .l>each gravels and sands 
cannot be held rigidly by any ordinary cementing nuiterial 
because, with the round, smooth snrfaces, there is little 
o])]>ortunity for any locking. 

560. Cleanness of Material. — Where crushed rock is used 

in the buihiing of roads it is important that these nniterials 
1)0 clean and tree fi'om dirt, chiy and rnbbish of any sort. 
So with gravel or sand, when these are called for they 
should be clean. Tn general, anything which works against 
uniforniitv of material should be avoided. 



EARTH ROADS. 

In the country in most parts of the Tnited States the 
gr(;atest nund)er of miles of travel for a long time to come 
must be nuule over eai'th roads. It is therefore of gTeat 
imjiortance that they should be built in the best possible 
nuinner. The projier construction of earth roads is made 
tli'e more important through the fact that when well built 
and well nuuntained there is no road easier on the team, 
the carriage or the ])arties riding, where speed is an im- 
])ortant c<insideration, than an earth road. 

561. Forming the Road-bed. — After the grade has been 
establislud and under-drainage provided where necessary, 
all organic material and stone should be cleared out of the 



453 



way and tlic I'oad «>,iv('T) the f(ti'iii and width dcsircid by a 
road inacliiiic sutdi as represented in Fig. 215, or by other 
means. 

Tlie ro'Ai] itself shoidd liave a width of IG or IS feet bor- 
dered (111 eillier side by ;i slrip of grass three feet wide, out- 
side of which shoidd lie the surface (]rains, wherc^ needed, 
five feet \vi(h' at the top, two feet at tlie ])ottoin and 24 
inches (K'C]), making a total width' of .'52 oi' 34 feet as rep- 
resentee] ill I'^ig. 2 14. 




Fig Jit — Show ui^ tios-, '•t c tioii ol 111 ( iillii 1(1 1> fi I t \\ i(l( boi'dcreii on each 
Hide with .i ti>(it ot Kiass, oiit^nio til winch aru placo.! tlin surlaco (Jrains 
when needed. Tlic center of thi^ road is three iiiciies luKlior than the sides 
at the srass. 



The ceiitei- of the roaddn'd shoidd be thoroughly rolled 
with as heavy a I'oJhT as practicable in order to compact it 
and to discover in it any soft jilaces. Jf soft places are 
found these should be filled and brought to tlu? projier 
lev(d. Jf the soft jilace is due to a different kind of ma- 
terial this should be removed and replaced liy other and 
better. 

The center (d' the finished road sh(tuld be two to six 
inches higher than the margins at the grass boi'der, vary- 
ing with the width of the track, in onh'r to give quick, com- 
])lete surface^ drainage, and tiiis should be built up in thin 
successive^ layers of as uniform material as possible. If 
eartli is brought in Irom the sides and ditches gi'cat care 
shonld lie exercised in distributing it evenly, and thor- 
oughly harrowing it ahead of tlu^ roller, so as to secure the 
necessary nniformity of textnre. 'Idiis is of the utmost im- 
])ortance in order to ])revent tlu^ formation of ruts. Thor- 
ough rolling should follow tlK' addition of each layer of ma- 
terial and shonld be kejit nj* until a hard, even surface has 
been secured. ' • 

28 



In iiiiikiiii;' (Mi'lli I'oiHls il is pjirl iciihirl v iiii|i<irl;iiil iml 
Id iiiiikc I liciii w i( In- 1 1 1,1 II ncci-ssii I'v hvcniisr I lie ii;i iTdw roinl 
is iilvvjivs iiiorc (|iiicl-,lv niid In'llcr <l r.i iiic(| ;iii(l hick ot 
(li'jiiiiiilic iiHin' lli;iii ;iii vl I'iii;^ cIs" will (|i'slni\ llir ciirlli 
roiid. 




l''lii. 215. View ..r.iMo iMic of luail i 



( 'IkiiiiiiIuii load Kniili 



II llic siill (■(Hiliilii'^ ciilihlc ^;;(;!ii's cxci'vl lilMi;' l:il'l!,('r lllilll 
(Hie inch, in (liiiinrlcr ^Imiild lir ihrnwii dill, nlhcrwisc llicv 
will I'onii nil^. 

If, ill csl iilil ish iiio ||i(. iic('css;irv iir;nlcs (Ui llic cnrlli 
roiuls, lills iiiiisl lie iikkIc, lliis lilliiiii' sliniihl hr (huic svs- 
Iciiiiil ic;ill\ , (Jislriluil iii;^- llic <';ii-||i in iinilnnii liivcrs whicli 
ni'c I iiiM-oiiiiliK liniicd will) llir i-nllcr ;is llic work jiro- 
orcsscs. 



562. Utilizing the Old Eoad as a Road-bed. Tii cases 

wlicrc 1 lie iir;i<l(' (Iocs not i-('(|iiir(' cluiiiiiiiii; ;iiii| \\|i('r(^ iiat- 
iinil iiiiilcr <lriiiii;i,iif is ;iilc<|iiiilc llic old r<);i(| IxmI may Ix; 
iilill/.cd ill ils ;ili'c:i<ly I raiii|ic(| ;iii(l packed condition upon 
wliicli lo liiiild llic new road. This may lie tilted wilji the 
road machine l»\' llirowin^' the loose ,'iii<l iineven portion ol' 
the snrla<'e oiit\\ar<l to loriii the shoulders. 'I'Ik'H iI tlKun; 
are still low places t liesc shoiihl he tille(| in mid I lioroii<>-|i|y 
packed with the roller, the use (d which is iiecessai'y cvoii 
where no leNcliiiii, is nccdcil, in order to disco\'er any soft 
s|>ots, (piitc certain to exist, and in oilier to <^\vc the foun- 
dation a more ihoronvdi packini:' than the wauoiis lia\'e se- 

Clll'Cll. 

563. Preparing' the Road-bed a Year or More in Advance.— 

It will generally he round a<l\aiilaii-eoiis lo jj,'el, the I'oad hed 
into pi'uper shape to recei\'e the siirraciii<;' material, whi'lhec 
this he jii'ax'cl or crnshed rock, a year or more in advance, 
iitilizini! the we;it heriiii! <d rains, tin- frost of wiiit<'i' and 
the tralhc to settle the roa<l hed, hiil di in '<•!,! ii<;' and assisting 
ihesr' a<4'eiicieH by a timely and judicious use of the liarr<)w, 
i'<iad iiiachiiie jiml roller. It is pa rl iciihi rly important to 
allow tijiie to inlervene where there has heeii mncli (illiiifz; 
necessary. 

564. Roads on Gravelly Loam. Where the soils -dvo a 
^^ravclly loam the hest earth roads are ])ossil)l(^ The I'eason 
foi' this is found in the fact that a iira\'elly loam is imnle np 
(»f iar^-e and small ;nraiiis in such proportions that when 
they are tlioroii<ilily woi'ked and compactc(| the ('oars(!r sand 
pai'tiejes work in hetw(.'ii I he iira\'el, and the line (day par- 
t Ich'S hel W( en 1 hose of sand, i n sii(di a wa\' t hat t here; is left 
almost no open space; iiiMJer tlic'^e conditions the water is 
shed the most rapidly and ciimpleteiy so that the road is less 
liahle to soften iiiiiler tie- trax'cl over it and it is less liahhj 
to he injured hy fiost. 

565. Roads in Fine Clay Soil. Wlu'ic t he .-.oil is a fine ad- 
liesive cla\' it is liar<ll\' |)ossih|e to make ii jioofl road with- 



456 

out the aid of foreign material. Of course by g-rading it 
into proper form so as to secure the needed drainage the 
road will be good wheu it is not wet, and under these con- 
ditions it will reuuiin fair much lunger than if not so pre- 
pared because, ^^'hen this soil has been once thoroughly com- 
pacted and dry, water enters it very slowly, so that it is 
only during long wet spells and when the frost is going out 
that the most serious injury to the road comes. 

566. Clay Roads Surfaced With Gravel. — Where gravel of 
suitable quality is available a covering of three or 
four inches, thoroughly rolled and packed, will very greatly 
improve the surface of a clay road, preventing it from soft- 
ening so readily with every rain and with the action of 
frost. Even sand and good loam, where nothing better is 
available, will improve the quality. 

In some cases burning the clay has Ix'cn practiced so as 
to render it less plastic and sticky, but this [u-actice will be 
one of the last to be resorted to at this time of chea]) trans- 
portation and high price of fuel. 

567. Sandy Roads. — The making of good roads in a coun- 
try of very sandy soil is extremely dithcidt on account of 
the nearly complete absence of binding ]n-op(>rties in the 
sand when dry. If there were any cheap method of keej)- 
ing the surface wet, sand W)nld make an excellent road. 
Even the rounded grains of beach sand for a short time 
after the waves have withdrawn are so tightly bonded that 
a horse may canter along the beach, nudving but little im- 
pression upon it. The water, however, drains away so 
rapidly from the coarse clean I'ounded grains that there is 
no longer anything to bind them together, and the foot or 
wheel easily sets them aside. When, however, there are a 
sufficient number of much finer ]:)articles commingled with 
the coarse sand grains a loam is the result whose water 
holding power is increased so that for a longer time the 
grains are bonded together by it, enabling the loam to form 
the better road. On the other hand, the amount of water 



457 

may be too great to jx-nnit it to act as a binding material 
and as the water-holding power of the clays is greater than 
the loams, they more quickly come into the condition, of 
over saturation during long rains and so the loam which is 
intermediate between the two extremes makes the best earth 
road, sand tending most of the time to retain too little 
water and the (day retaining too much for tight l:)inding. 

With this principle to direct practice it is clear that if the 
right amount of finer soil particles can be ol)taine(l to in- 
corporate with the sand of sandy roads their firmness will 
be increased. It is unfortunately too often true that in 
districts whei-e sandy roads prevail there is no clayey or 
loamy material avaihible, either to incorporate with the 
sand or to place above it. 

568. The Use of Straw, Sawdust and Tan Bark on Sandy 

Roads. — It, is well known that these materials when applied 
to sandy roads have temporarily a beneficial effect. The 
fundamental principle underlying this im]>rovement is that 
stated in the last paragraph; that is, in the power they 
have of maintaining a higher ])er cent, of water in the sand, 
Avhich is necessary in order to bind lhe grains together. 
The sawdust, tan bark and straw act in two ways to main- 
tain the needed amount of water in the sand. At first 
they act as a mulch, lessening the rate of evaporation from 
the surface. Later, when they begin to disintegrate, they 
form a humus-like material, in its physical effects, which 
increases the capillary power and diminishes the rate of 
percolation downward after rains. 

The reason why these materials are only temporary in 
their effect is because they rapidly decay, being C(uiverted 
into soluble salts and gaseous products which finally leave 
the sand as if notliing had been added. 

569. Road Gravel. — It occasionally happens that natural 
gravel beds are found Avhicli possess the right characteris- 
tics for making roads, and when the gravel is just right ex- 
cellent roads mav l)e made from it. 



458 

Tliere are several ini^xirtaut features wliicli a good road 
gravel must possess : 

1. There must be one prevailing size of pebble in suffi- 
cient quantitv so that when tlioroughly rolled they press 
against one another. 

'2. There must be enough of the liner sizes of coarse sand 
and fine gravel to fill the voids between the coarser gravel. 

?). There must be enough of tine loam to till the voids 
between the coarse sand and fine gravel and retain a suffi- 
cient amount of water to bind the sand grains together and 
prevent their rolling. 

4. The coarse and iine gravel and the sand must be made 
up of more or less angular fragments in order that flat 
faces of rock may set together and thus levssen the danger 
of rolling and of crushing under the weight of the load. 

It is not possible to give specific, concise directions for 
identifying a good road gravel, but a man who has seen 
and worked with it readily recognizes it. 

570. Clean White Gravel Not Suitable. — It will be appar- 
ent at (Uice that the several chnraeteristics which have been 
point(Ml out are not likely often to occur together in just 
the right ratios; and so tliere will be all possible gradations 
from the ideal gravels to those which will not answer at all. 
Indeed it must be said that most gravel beds have had the 
finer materials so completely washed out that only clean 
sand and gravel remains ; and Avhen this is true it is useless 
to try to nudvc a road with it. Such nmterials can only be 
used to temi)er a road which is too clayey in its texture, 
by reducing its water capacity. 

571. Texture of Gravels Altered by Crushing and Screen- 
ing. — It happens in the majority of cases that much of the 
gravel is too large and too rounded to permit close packing 
and fast binding. AVhen this is true much better qualities 
may be secured by using either the crusher or the screen 
or both together, one form of which is represented in Fig. 
210. It will be at once apparent that where much of the 



459 



gravel is too odiii'sc. to v\ui it thrduiili the cnislicr so as to re- 
(liico the material t(» a more uniform size and at tlio same 
time to increase the aiiiiiilai-itv of the fraiiments will make 
a miicli hetter road material to nse ( itlier hy itself, or as a 
tempei'iiiii' material. 




Ficj. 216.— Champion lock ci usher and i>cieeu. 

572. Some Gravels Contain Too Much Clay. — There are 
many deposits of gravelly clay which it might appear would 
make a good road material, but the priuciple must be kept 
always in mind that too much of a too fine uuiterial will 
take in and retain so much water that the l)inding quality 
of the Avater is lost. These gravelly clays occur in many 
of the hills of the glaciated portions of the United States 
and throtiiih which roads are often cut. 



573. Gravel Roads. — In the construction of a gravel road, 
as in that of a stone road, it is of prime importance to se- 
cure first of all a properly shaped and thoroughly rolled 
and firmed road-bed before any gravel is laid on. When 
this has been done, and a suitalde gravel has been found, 
the next step is to spread evenly over the surface and thor- 
oughly roll a layer which, when finished, will measure three 
inches thick. 



4(10 

111 t'lR' rolling it will \)c iiii|)(irt;iiir ro tinii the outer edg-es 
of the gravel first in order that r'ue rolling may not force it 
outward and destroy the slope. Should the gravel be too 
dry to pack it nmst be moistened or the work he suspended 
to take advantage of the rains. 

To make a good road there sliould lu' iiut less tliaii three 
3-incli layers, and usually four will he hctter. Of course 
a road 6 inches thick will he a great iniprovenieut, and 
often where the travel is light and the road-bed thoroughly 
made, thre(> inches of good gravel, well ])laced, will make a 
great improvement in tli(> road, serving as a wearing sur- 
face. 

Wlier(^ the gravel must he crushed and screened to secure 
the ])ro[)er sizes the revolving screen represented in Fig. 
210 should be used and should have two sizes of holes 1.5 to 
2 inch and .'> to 4 inch in diameter. The coarsi-r size of 
gravel will form the body of ihc rojul while tlu> Huer will 
have to be discarded unless it happens to he of the right 
quality to use as a binding material or in making a bicycle 
path along oiu' side of the road. 

574. Koads in Swampy Places. — it occasionally happens 
that roads must be built in ])laces which cannot be drained 
and which are too soft to peruiit of the construction of a 
solid earth foundation. A co, union way to meet this ty])e 
of coiulitions is to lay a fi)iiiidatiou (if logs, poles or even 
brush, having the desired width ol rh,' road and of suifi- 
cient body to enable an earth or gravel road to be built u})on 
it. When such roads are built iu situations where the wood 
is kept constantly beneath the water it <loes not decay and 
a road of considerable permanence and solidity is secured. 

Where logs are used care is taken to arrange them at 
right angles to the direction of the road, parallel Avithi one 
another and like sizes side by side. The depressions be- 
tween the logs are filled with smaller logs or poles, whole 
or split, while these in turn may be covered with twigs and 
limbs forming a mat up<»ii which the earth or gravel road 
is built. Upon this mat of wood is usually first thrown 



4<;i 



till' iii;ir('ri;il rjikcn tiN.iii (litclu^ oil cirlicr side iiiadc for 
<lraiiiai>e, bnil(liiii>' the earth or liravcl roa<l iij)oii this after 
it has first been well spread and iiniieil. 



STOXK IJOADS. 

Stone roads of one form or another date back to and pos- 
sibly beyond Roman times; and Fig. 217 represents two 
types of the extremely massive and substantial roads 
which were bnilt ten or fifteen centuries ago, some of 
which still survive. These roads had a width of 30 feet 
and pavements of heavy stone at the bottom and often one 
or more layers of stone bedded in cement to make the road 
water ])roof. One ty])e of construction which they fol- 
lowed made tlie road consist of four lavei-s : 




Fid. 217.— Two t,vp(»s of Ancipnt Roman stone roarls. (After Shaler.) 

1. Two or three courses of flat stone or, if these were not 
obtainable, of other stone, generally laid in mortar. 

2. A layer of rubble masonry or coarse concrete. 

3. A finer concrete u])on which was laid 

4. A layer of ]»aving blocks jointed with the greatest 
nicety. 

It is stated that with many of the <>Teat roads the paved 
portion had a width of f<i feet bordered by raised stone 



462 



ciiuscways cmtsldc of which, on cncli si(h', avcih' uiipaved 
si(h>-waT8 Ciich ciiiht tcct \\i(h', Jiiul the |):i\('(| \v;iv soiiic- 
tiiiies had an a<>,iii"c<iatr thickness of thi'cc led. 

575. Macadam Roads. — The use of crushed rock in road 
hnihliiiii is al h'asi as ohl as Roman liistorv ; hnt as, (hiring 
ihc (hirk ai;('s, litHc road hnihlini^ (d a pci'iiiancnt character 
was practiced, the art had to he i'e\ived in nnxh'rn times 
and ahont 17(i-l- th(> French eni;ineer 'rresatiuel appears to 
ha\'e inti'o<hice(l into l^'rance the t_V])e of I'oad represented in 
.Fii>'. 2lSj consistini;' (d' a stone ]>avement co\'ered with two 
or three Indies of ernslied rock as a facinu'inateriah Alter 
being' intro(hieed into Fnghind and Scothmd, where the (U'- 
tails were modilied and perfecled hv TcMoi'd ahont lSj>(), 
tliis tvpe of stone constrnclion came to he known as tlic 
'^l\dford roaih 




Fig. 218.— T.vp3 (if road iiitroducod into Fimiicp by Trcsatrupt about 17t)4. 
CAftiu- Sliiiler.) 



Maca(hinrs work '.legan somewhal eai'lier ihan '[".dtord's 
in iS'Ji, and to him apparent Iv is (hie ihe i(h-a thai when 
any r(tad-hed is thoronghlv mnh'r (lraine(l, so as to remain 
]iermaneiitl_v har<K then crnshe(i stone ahme may he nsed, 
the pax'ement (d K(unan praclice hecoming nnnecessarv. 



576. Construction of Macadam Roads. — After the fonmhi- 
tion for the stone road inis heeii comph'ted the hoi'(h'r is 
left Avitli a shonhh'i" (d eai'th on each si(h' as re|)i-esente(l in 
Fig. r»l'.>, hetweeii which the r(»a(hhe(| is co\-eri(l with i\ 
Uiyer of crushed voi-k as nearly one size as i)ossihh' and 
three or four inches thick. This layer is next thoronghly 
roHed and then coNcred with eiiongli of tinely crushed rock 
to fil] the voids between the hirger fragments. This ma- 
terial is worked in with the roller and water until a solid 
bed has been foriiu(h 



403 



After llic fii'st l;i\ci- li;is l)cc;i plnccd llic scccikI is jip- 
jilied ill the siiiiic iiuiiiiici-, ritllcd, jiiid llic hiiidirio- matcriai 
jif)j)li('d {iiid aiiiiiii ndlcd, until thorough coiiscdidatioii has 
been secured. 




Fig. 210.— View showing the road bed, in the foioKround. shai)C'<i with road 
grader and receiving tlic foundation Jajer of crushed rock 4 inches thick. 

577. Fitting the Road-bed. — It is of the utmost impor- 
tance to have a thoroughly firmed and seasoned road-bed 
put into proper form and well drained before the stone sur- 
face is to be apjilied, and to do this most economically it is 
well to do all of this })relimiiiarv work a year or more ahead 
so that traffic, rains and frosts shall have an opportunity to 
do the work of consolidation, and to discover the soft places 
which may exist. In short, the formation of a good earth 
road to be used for a number of years as such will generally 
be found the best and most economical ])r('])aratioii for the 
stone road. 

578. Forming the Shoulders. — The formation of the shoul- 
ders represented in the foreground of Fig. 210 is best done 



404 

with a road grader or road inachine. With this tool th(! 
surface of the road-bed is prepared at the same time and the 
shoulders left in such shape that very little hand labor will 
be required for the iiiiisliins>' touches. After the shoulders 
have been roughly foruied and before the tiuishiug' touches 
are given the roller should go over the road-bed to make 
sure that it is properly tirnuMl and that there :ire no soft 
places. 

579. Kinds of Rock for the Road. — Practical experience 
has demonstrated that the best rocks for road making are 
the dark green, black and dark gray trap or igneous rock 
such as are known in common language as "nigger heads" 
in glaciated countries where hirge bouhh^rs are common in 
the fields and cuts of roads. They are tough, fine grained 
rock, much less brittle than most others, which yield when 
grinding upon themselves and under the wheel a fine rock 
flour whose texture is sucli that it holds the nccdi'd amount 
of moisture to nudvc it l)ind together well, and consequently 
a road built from these fragments sets sooner than almost 
any other crystalline rock and hence is subject tr) less in- 
ternal wear. 

Next to the trap r(jck in value foi- road building purposes 
stand the closer grained liond)lend-liearing sycuiites and 
gneisses which are species of granite where bornl)h'ud takes 
the place of mica of the true gi-anites. It is the class of 
dark minerals allied to hornblend conii)osiiig much of the 
trap rock referred to above which makes that the best road 
stone. 

Next in order stand the true granites nuule uji of quartz, 
feldspar and mica, and tlieii- gnt'issoid varieties. The best 
of this class of rocks are the close fine-grained varieties 
having the least tendency to l)reak into thin layers, giving 
flat instead of cubical blocks. 

To the granites and syenites with their banded or gneiss- 
oid varieties belong the lighter colored and flesh colored 
boulders which are usually associated with the ''nigger 
heads" of alacial drift. 



465 



Tlio ('liiof (litticiiltv 'vvitli syenites luid iiriniites for road 
inetal is their brittle, iiiiyieldiiiii (jujility and coarse crystal- 
line structure which makes theui i^riud and pound up into 
a coarse sand without a sutheient amount of the tinest dust 
to i>ive it the needed water-liohliuii- ])ower to permit it to 
|»roper]j hind the pieces together. The road-bed fails to 




Fig. 220— View showing where four inchc.'; of cru.'^hed rock for wearing surface 
is bsin'j; built upoa f.jur inciies of roail-^r.ivel as founiritiun la^er. 



set quickly and the internal wear is larger while there is a 
greater tendenc^y for ruts to form in wet weather and for 
the surface to ravel or throw out loose pieces in a dry time. 
Next to the syenites and granites in general availability 
for road metal stand the close grained hard limestones 



4G() 

whicli break into hard, clean blocks and fragments with 
sharp edges and little material which will rnb oif under the 

fingers. Any reck which crnshes rcndily into an earth- 
like or sandy material will not answci- for road work. 

When a good road limestone wears down under the 
wheels, the horses' feet or the rollci-, a loamdike jvowder is 
formed which holds the riglit aiiiouiit oi water for good 
binding, and besides this it ajjpcars more quickly to pass 
into that cementing stage which in nature cements beds of 
loose fragments into rock. 

The chief objecti<tn to limestone as a road metal is it^ 
softness, which ])ermits it to wear away ra})idly, leaving 
the surfac(> <liisty in dry and ninddy in wet weatluM-. 

The extremely hard and brittle cpuirtzite which throws 
oif ansiilar bits under tlii' blows of horses' feet and the roll- 
ing of wheels make one of the poorest road materials be- 
cause it too nearly -[wssesses glassdike brittleness and the 
dust is too coarse and sand-like to hold the needed water for 
binding. 

580. Foundation and Surfacing Stone May be Different. — 

Where there is in tlu' locality a r<iek whicli does not make a 
good wearing surface bnt which hinds well, like limestone, 
this may be used to advantage for the foundation of coun- 
try roads, thus making it necessary to import only the wear- 
ing surface layer. 

581. Sorting- Boulders Before Crushing. — In h)calities 
Avhere there are many boulders available for road work 
it will often be pr;icticable to sort these when hauling them 
to the crusher in siu-h manner as to use the lighter colored 
varieties for the fonndation, reserving all of the "nigger 
heads'' for the surface layer, and in this way increase the 
efficiency of the material. 

582. Using Limestone for Binding. — Where only granitic 
rock and quartzite are available for road work and these do 
not bind Avell, it will often happen that the limestone of 



4»i7 

tlic Jticalitv jiiay be criislictl tiuc to form screenings and 
us(m1 to i>reat advaiitag-c as a hinding material to hold the 
harder rocks nmre securely in place. This practice would 
be C'speeially desirable for the foundation layer where it 
could not be converted into dust. But in localities where 
both limestone and the harder i-ock are availal)le, but where 
the limestone can be obtained at much the less cost, this 
may be used alone for the foundation and as a liinding nui- 
terial for the surface layer. 

583. Roads Made Without Binding Material. — It was ]\[a- 

cadam's practice in road buihling to strictly forbid the use 
of all binding material whatsoever. He preferred to wait 
for the general traffic over the road to develop from the 
wear of the crushed stone, both superficial and internal, 
the necessary amount of rock flour to do the work of filling 
and cementing. While this work was in progress the road 
was given constant supervision to keep it in proper form. 
At the same time the hliing and binding material was be- 
ing sh»\vly ]iro(hiced thei'e was brought upon the road with 
the wheels ami hoi'ses' feet a considerable amount of earth 
"which slowly A\'orked downward and united with the rock 
flour to com])lete the consolidiition. .Macadam certainly 
secured in the end a better road by this nielhod than was 
usually secured with the use of the then available binding 
material. 

It must be rememl>ere(b lio\ve\-er, that in his time rock 
were crushed by hand and little fine matcM'ial was made to 
use for binding, Avhereas with the modern rock crushers a 
large amount of this nnitei-ial is produci'd whicli must be a 
dead loss if it cannot be nsed for l)inding and surfacing, 
and it is (|uite certain that had .Macadam \\:^i'(\ our modern 
rock crushers he would have availed himself of the screen- 
ings. 

584. Use of Sand for Binding. — The great readiness with 
Avhich clean dvy sand works into and fills the \-oids between 
the stone of a road, the ease with which it mav be handled 



408 



and the readiness with which it may < if ten he obtained, 
leads to its occasional use as a binding material in macadam 
road. The coarse silicions sands, however, have very little 
cementing quality, they do not retain water well enough 
either to make the road shed the rains nor give the surface 
tension of water much ojvportunity to bind the grains to- 







^/. 



Fig. 221. — View .sliowin<3: tlio binHini; matprLal or screenings being applied to tlie 
found iiiou layer of crushdd rock. 



getlier firmly; consequently the l)est results cannot be se- 
cured when it is used. 

If loam is used there is danger that it will pack in the 
upper surface of the layer of stone and prevent even the 
combined use of water and the roller from working it to 



4(>!) 



the bottom so as to coinplctclv lill tlic \'(M(1s. There' is the 
still further dauiier that it will work in hetween the flat 
surfaces of the crushed rock, hol(liu<>- tlieui a])art vo such au 
extent that liea\'v loads A\ill produce too iimch rocking of 
the pieces and quicklv lead to tlie fornnition of ruts. If 
the loam c(,iild \\:' li;i<l in a dry cMiidition, such as is usually 
the case wirli f!ie screenings ;;nd llie sand, it wcidd he possi- 
ble witli di'v r<:]Kiiii- to nciwlv eom|)letely lill the voids so 
that the sul)se(pient use (d' water wonid, with the roller, lead 
to ii'Ood results. 

585. Limestone for Stone H,oads. — There is no doubt that 
crusiied limestone allhouuh a s(d't I'ock will make an excel- 




FlG. 222.— View of dist,ril)Uliii^ cart lu'iiii;- raifi^d to spread cruslird rock. 



lent countr\- i-oad where the traffic is not heavy and the 
use of it should bi' encouraged wherever suitable (juality of 
rock is availalfle. There is no rock which breaks in better 
S9 



470 



form or which liiiids ;is well and sots as ({iiioklv. It is 
)"oa(li]y quarrii'(l and piit^ in shape fur the crusher; and the 
j)ower ro(inirt'd lor crnshing hoinj;' small makes it less bur- 
densome tor towns to invest in the necessary machinery. 

It is trne tlu;t the road wears rapidly under heavy traffic 
and the surface becijuics dusty in a dry time, but not more 
so than clay roads do. It is tnie that careful road engi- 
neers advise against its use, hut it is usually from the stand- 
point of city r.nd suburban tratlie rather than from that of 
the pnrely country road. 




Fig. 22.'5.— View of distribittiitr curt spread iiitr cinsiied rock on the road. 



586. Spreading the Rock on the Road-bed. — It is import- 
ant that Ihe crushed rock should be laid down on the road- 
bed in a sheet both of uniform thickness and uniform den- 
sity and where this is not done the road is quite certain to 
roll to an nneven surface which will nud\e it necessary to 
add more nuiterial in some places and remove it in others. 
But this will unnecessarily add to the cost of the road. 



471 



Not (iiilv I liis. 111 It V, lii'ii a Wiii>(iii-I(i;i(l of s', one is all (Iiiiii]K'(I, 
ill (iiic |ilacc. Iciviiiii,- il tnr a man to spread, it is cerlaiii 
tu (K'cur tliat all ot* tlr/ drsl ami iinr iiiatcria.ls not ronioved 
hy the scrc:'ii will Ave.]} into ili- voids at tlif jjlaeo where 




Fic. 2il.— V'Knv of siiificitii; cnis!ie'1 r.)ck as Ipft, by tlio di^tributinir cart on the 
roail. 'tiir w.itcli. 1 mcliea in (Jiainetjr, f:e.V(is as a scale to show the size of 
til 3 lock fiairiutiii.-. 



the loa<l was left and this will give rise to a sjjot more eoui- 
pacted than the halanee of the road and hence when it eunies 
into service two nits or de})rcssions ai'c liahlc to form one 
on cithei' side of the harder S])ot. 



472 



'I'o ;i\-<ii(l llicsc (lifHcultics ;iii<l to s;i\c time in sproadiiiiT 
the inaterial the distributinfi' cart repres(Mited in Figs. 222 
and 22;') has been devised. In it can he phiced two cnbic 
yards of rock, and after tilting' the l)o.\ as shown in F\<j^. 222 
the end hoard may l)e opened to siu'h a width as lo (h'posit 




Fig. 225.— View of tlie smlaciuK rock aflor it has Ijcoii pacliod b,\ tlio roller. 



a TiTiiform layer of any (h'sire(l tlnckness while the team 
travels alon<>' at a slow and nniforni pace. Fii>'. 224 is a 
view showiii<i how tlie sui'facr was left hy the di.-t rihntini:; 



47;; 

cart and tIic watch is a scale l)v wliicli the size df the pieces 
may Ic jii(li:c(|, its (li;iiiictcr hciiii: a ti'iHc less than two 
inches. 

587. Thickness of Layer. — Tlic thickness of a layer 
jihiced at one time shduld \'ary somewhat with the siz(! of 
tlic ])ieces, the (h|)th heiiiu' <ii"eater witli the hirc'cr frag- 
ments. With pieces of tiie size shown in Fig'. 224 the layer 
when packed shonhl not l)e greater than fonr inches and 
three inches will pack more (piickly and closely than four 
inches. A too thick layer tends to form a crust on the sur- 
face, making it diiiicnlt to till all the voids below com- 
]»letely. 

588. Rolling. — The function of i-olling is to arrange the 
fragments in the positions of the greatest stal)ility with ref- 
erence to the rolling of wheels and the tramping of horses. 
The first effect of the roller is to bring the pieces nearer 
together and to rednce the size of the voids. This is clearly 
brought out by the two photo-engravings, Figs. 224 and 
225. 

There is one otliei' iii!po)-t;;nt thing Avliich rolling slunild 
secure and that is to pnt the several ])ieces of stone together 
in the ]>osiTio]is of the most stable equilibrium; that is, in 
positions such' as to make certain that they shall not tip 
oi' turn when the stress of the wagon or team is l)ronght 
u[u<M thein. 

589. Size and Weight of Roller. — The diameter of the 

roller should l)e lai'iic to pre\"( n1 it from shoving the stone 
forward as it nutves and in oi'dei' that the thi'ust may be as 
nearly directly downwai-d as possible. It will be observed 
that even the front avIk-cI of a loaded wagon often slides 
rather than rolls wl;c)i coniinu up;»n the unpacked layer of 
rock on the i-oad, and such ino\'einent cannot do ])ro])cr 
packing. 

There appears to be a lack of aiireement between prac- 
tical men regarding the proper weight of the roller, some 



474 



advocatini>' n roller of .')..") tu ,').,") tdus, wliil;' otlicrs Iwtld 
that oiily one of 15 to 20 tons wcuilil will s"i'v.' t'lK- jMirpuse. 
Others advocate a Huht Avciuht 1o ]);'iii!i with and a lu'avior 
one at the close. 




Fig. 226.— View bhowii 



irse I'dlliT at work coniparl iuK the road metal. 



590. Amount of Rolling'. — Tlic only "cneral rnle which 
can be given in regard to tlu^ amount of rollini;' a given 
layer slunild receive is that the work should h;' continued 
until the stone cease to move in front of the roller o^- un- 
til the roller no longer sensibly dej)resses the bed and it 
has become hard and smooth. It should be kept in mind, 
however, that the i-(»ad neay be rolled too much, or until 



475 

the stone a^aiii briiiii to iiioxc. 'I'liis is most likely to oc- 
cur wlu'ii the stone is too di'v. 

591. Manner of Rolling. — 'I'W rollini; should heoiu at the 
outer sides of the road, paekiug tlu^ stone first aiiainst the 
shoulder. If this is not done the fact that the road-bed 
is hii>hest in the center Avill lead to flattening- the slope and 
thinning' out the rock in the center through a side creeping 
of the material from under the roller. 

592. Kind of Eoller. — Inhere are three methods of consol- 
idating the layers of stnne put into a road. The flrst, now 
largely abandoned as being too expensiye and too uncertain, 
is to allow it to be done by the natural traffic. The second, 
also being abandoned as too (>x])ensiy(\ is the use ci a 3.5 
to 5-ton horse roller; and the third, which is regarded the 
cheapest and best, is with tlie aid of an S to 20 ton steam 
roller. 

The safest indications seem to jxiint to ihe use on coun- 
try roads of an .S to l()-tt)n steam roller as most satisfactory; 
although good work eau be dune wilh the horse roller of 
half this weight which nuiy be made heavier or lighter by 
taking on and laying off weights Such a roller as this is 
represented in Fig. 22() which, naked, weighs 3.5 tons, 
but by the addition of castings to the inside of the roller 
may be increased to 5.5 tons. This roller has the frame 
and tongue so constructed that the team may be turned 
without reversing the roller, a very ini})ortant feature. 

It will be readily seen that the use of two men and two 
teams must make the service of this roller very expensive, 
and when the disturbing effects of the horses' feet are re- 
called it becomes clear that the steam roller easily managed 
by one man is much better. 

593. Rock Crushers. — lh\t\] recently all rock crushing for 
road work has been done by hand and hammer, and in the 
days of slave labor Avhen the man was a machine which 
managed, fed, cared for and i'e]>r(i(!uced itself, it is clear 



470 



ho-A' siK'li I Icrruk';!!! tasks as rlic aiiricnt liuinan roads could 
be accomplished. But happily, the use of steel aud iuani- 
inate forces is freeiug uuiu from such drudgerv ; aud in 
Figs. 227 aud 228 are two views of a rock crusher at work, 
})reaking stone, sorting it and delivering it into hins 
where it may easily he dro])]ic<l into wagons for delivery 
upon the road. 





.'^-r-' 









. ^ 

*?i-.^ 



Fk;. 227. — View of No, :■! Austin (^nisiipr, with rin olviii;,' serpen breaking' boulders 
for road : aud wa'jou loadini; cc>ar»est jjrade of brolien stone. 

At the time these vievvs were taken the ciMislu r was be- 
ing driven hy a 22 II. 1*. tra.ctiou eiigiue aud was crushing 
rock at the rate of 100 wagon loads per day. The material 
is separated into three sizes, the coarsest used for the foun- 
dation, the intermediate for the weariui>' surface and the 
finest as binding aud surfacing material, and Fig. 227 
shows a wagon loading with the foundation size, and Fig. 
228 with the screenings or binding material. 

There are various forms of crushers on the market and 
Fig. 216 represents another type. 



594. Eevolving Screen. — 'I'lu- rcvc.lviiio- screen is an indis- 
pensable attaehnient to ;i rock ci'iisliei-, because a yood read 
cannot, be nnid(> \vith the niisdrted material, fnr with this 
method of putting- the (tusIkmI rock upnn the road the fine 
materials are ccrtiiiii to work (h)Wiiwar(l niid the coarser 
frag'ments to couk" to the surface. It sliouhl he th(n"ouglily 
nnderstood too that the cluite screen will not do the Avork. 




Fh;. 228. - Side view of No. 3 Austin ('rusher ami \vat,'oii loadiiitt screeiiiugs. 



595. Earth and Stone Road Combined. — Where it is de- 
sired to chea])en the construction of stone roads it is ]irac- 
ticable to make the central portion 8 feet wide of this ma- 
terial and then have on one or both sides an earth road 
of eight feet, giving a total widtli of 1() or 24 foet to the 
margin of grass and ;»() feet to the side ditches. The most 
serious objection to this condjineil jilan is the securing at 
all times of sufficient and (piick surface drainage. 

The chief difficnlty which will arise in the carrying out 



1 7S 



of lliis |il;iii will cniiic iVdiii ihc iciKJciicv of siiiiiiiicr Irnllic 
oil llic liiii'i'dW (■.■irlli i'(i;i(| Id i;() sii |iri'sisli'iil I V In niic I I'lurk 
;is If) (|c\cl(i|( wliri'l :iihI IimiI wjivs (Ici'j) cimii;;!! In pfcvciil 
surrjicc (Iniiiiii^c. Tlic I'licl lli;il iIu'sImih' i-diid iiinv (toiiu; 
into sci'N'icc wlicn Ihc ^rniind is wtI will niilv Ic^scii llic 
IcikIciicv III (lc\"li)|» llir evil |iniii|c<| oill liiil iiol [irrvcMl 
il. I''(ir wiiilcr ,'.('i'\'ic;' in cnM cliiinilcs il srs'ins cli'iir llinl 
llic ciirlli l'ii;i(l will II ' likcl\' In (risiiri' li'lli'i' .slciiiliiiiii'. 



L..B^^ 



flAMI^ "V "TI ^.>--" 

I DIICH I ■->*- 



efT a r T 

--^ •• bTONL* -<o7:p~^ B . ; , 7 .^HANK 

I DITCH I 



I en 

R/iMn \,..a.' ! 

I oil CH 







i.f^ 



^n. 



rYs^Sr^^ff^^'^S^^^^S^^B?^-^^^ 












i 



Path II Iran 1 1 Him (I 



vSioiu'Hoik) 



1 1 Foul 
! Path 



l''l(is. i;:i'.t. I •lji>;riniis s'lmwlii^' |irulllcs i<\' cmi'IIi .•iimI sfdiic i":itl coiiihliicil. 



596. Telford Foundation. W'licn il is ncccssiirv lo l»iiil(l 
Ihr r(i;iil wlirrc ill!' i^niund is snl'l llicii il ni;iv li!' I)i'sl lo 
iii V il found ill ion ol' liiriicr si one iis wiis I lie pMicnil |)riU'l ice 
willi llio Ivoiiiiins iiiid willi llic iMi'^lisli cni^inccr, Telford, 
M'li(>sc niinic is now iill;iclird lo lliis lypc <it i"o:id lonndih 
lion. Tlic |tii\iii!4- Mocks slnmld he niiifcnii in sl/.c, liiid 
in rows iicross llic roiid iil'icr il li;is hmi ii,i\'cn IIk' projXM" 
slojic, llic |iicccs l)rc:ikiiii; joint-.. Tlic slmics slimild not 



4Tl> 



oxct'Cfl 10 inclics ill lciii;lli, Ci iiiclics wide on tlic Koltoiii 
and 4 inclics at the to|), tlic tliickncss 1i('iii<i' 4 or 5 iiiclies 
for a road S inches thick. The surface of the pavement 
foundation slioidd lie as ex'cii as praclicahle and the void;-' 
filled with hroken stone. It is nec;'ssa ry to have each j)iece 
tboroujihlv hedded before the iiiacadani material is added 
so as not to he tilt((l on the surface. 





• ^^■^■.■^'i:! rfTWi'ae< "Tgia 



Fk;. 2;il) — View siiowint; i<ja(l with the -tone [idi i mn ui t lie foreground nearly 

completed. 



597. Culverts. — Culverts are necessary for carrying un- 
der a road the water fiw.in adjacent fields which collects as 
surface drainage in limes (d' heax'v rains and meltiiig snows. 
The ])erinanent loniis are made of sewi-r tile, cement tile, 



480 

cast iron sewer ]>i]K- (ir <»f stone. \\'(i<i(i slmuld only be 
used as a tempi )i'ary expedient. 

Where tlie amount of \vat(M' to lie conveyed is small so 
as to demand only one, two oi- three li'-inch sewer, or ce- 
ment tile, it will nsnally he cheapest to nse these, hut Avhere 
a water-way deniandin<>' a cross-section of more than S 
scpiare feet is necessary and where stone are avaih^hle, it 
will be chea])est to make it of arched masonry. 

Where the culverts ai'e of sewer pipe there should be 
not less than J!S inches of earth in tlie I'oad al)ove them to 
prevent erushini;'. 

The cast iron pi])e is the safest tf» use and cliea])er than 
either sewer or cement tile whi'n diameters above 10 inches 
are required. 



VIAlXrKAAACK OF CorNTIiV liOAOS. 

Important as the matter of construction of ^^ood roads 
is, it is, or should \n\ secondary to that of maiiitenance; 
when a i>()od tiling' has bet u made which is designed for 
permanent service it is clearly a matter of sound business 
policy to ]U'ovide whatever economic iueans is ])racticable 
for keepinu it in order. 

598. Section Men Necessary. — In the maintenance of 
railroads it was early leiwiied that two oi' uku'c men pro- 
vided with propel' tools must he employed by the year, per- 
manently or as long as they i-enderi'd ethcient service, to 
care for and keep in order a certain number of miles of 
road. It is the business of these men to daily go ovei- their 
section and kvc]) it in iirst class re])air and their tenure 
of office is only conditional upon their (hn'ug this satisfac- 
torily. 

It is self-evident that good country roatls can only be 
maintained by adojiting and kee])ing in force a system 
wliieh is equivalent to that found indis])ensable in railroad 
maintenance. That is, men competent to do the work, 



481 



provided with tlie ncccssarv imtlioriTv, tools ami iiiaterials, 
must have C(jnstaiit eui[)h Anient at a price wliieh will per- 
mit them to devote tlieii- time to it, and thev must be made 
responsible for llie maintenance of a cei-tain inunber of 
miles of road ''>()") davs in a vear. 




Fig. 231.— View of country stone road with foot path on one side, near Maybole, 
Ayrsliire, Scotland. From pliuto iu l.'9.i. 

599. Road Master. — in the conntrv road service it will 
be necessary to liav(^ one man who correspoiids in duties 
and responsibilities to the "Section I>oss" of tlu' railroad. 
He must be com])etent, tenii)eratc and in every way relia- 
ble and trustworthy. He mnst have a practical knowl- 
edge of the princi])les ae.d details underlying the main- 
tenance of o()od r(»ads and at his coniniand the necessary 
authority, assistance and appliances foi' doing the work re- 
quired. 

600. Width of Tires Controlled. — When we come to have 
a svstem of ^ood roads an<l the means for maintaining them 



482 

it will he necessary to have ordinances regnlating the width 
of tire and diameter of wheel which may he nsed on the 
roads when carrying- speciiit^d loads. ]n p]nrope, where 
better roads are found and a lictter system fur maintenance 
exists, there are ordinances which tix the width of tire to 
be used with given loads. In iUu'ai'ia the regulations are 
as follows : 

Two wheel carts witli two horses, 4. 1-'!.'! inch tires. 

Two wheel carts with fonr hoi-scs, (i. ISO indi tires. 

Four wdietd carts with two horses, 2.r)!)(i inch tii'es. 

Four wheel carts with four horses, 4.1-]o inch tires. 

Four v.'heel carts with five to eight hoi'ses, (>. ISO inch 
tires. 

Carts with more than four iiiid wagons with more than 
eiglit horses are not allowed to nse th(^ roach' without a 
special ])erniit from tlie aulhorities. 

Other countries of the Old W'oi-ld have found similar 
ordinances necessary and it is clearly rational and just 
tJuit su.ch matters should he r(^i>ulated, for othei'wise one 
man nuiy easily ])ut in jeop;!rdy the interests of a whole 
community. 

601. Maintenance and Repairs. — A sharp distinction 

should ahvays he luiide hetween the nniintenancc? of a road 
and its re])airs. it is only when some accident has oc- 
curred to seriously injure a road or when, from long 
neglect, it has become well nigh Avorn out that re])airs are 
needed, but the daily touching up of slight defects and 
places of evident wear constitutes maintenance. 

602. Good Maintenance. — (lood maintenance will con- 
sist in daily attention to all the details wliicli are necessary 
to keep a section of road up to the standard of ])erfection 
practicable to its tyjie, influenced hy its local surroundings 
and conditions. It must consist in (1) keeping the road 
in proper form; (2) in adding materials to the wearing 
surface where needed; (8) in kee])ing the road surface 
and drainage channels clean ; (4) in keeping the road sides 



483 



free from weeds inid o'.iierwise neat; (.")) in cariuii' for and 
maintaining' road trees if tliev are grown; (G) m main- 
taining the jjroper conditions in winter in regard to snow. 

603. Maintenance of Earth and Gravel Roads. — The first 

reqnisite for the n'aiiit;'n;inee of any road is the knowledge 
which can he gained hy going over the road whiki or im- 
mediately after it rain-. Ohservations at this time 
will show the road master wliere the most serions defects 
exist jind he slumld iiia!-:e careful note of them to use in 
directing his etl'orts a.s so(in as the weather permits. It 
shonhl therefore he ihe hnsiness of the road master to study 
his roads in wet weal her and he should he equipped with 
clothing, etc., in a way which will ])ermit him to do this 
witliont idsk of injurv to heahli. 




Fig. 232.-; View of French country road 20 fePt wide, showing piles of crushed 
limestone used in luaiutenance. PLoio. in lt9j, near (irignon. 



Whenever ruts or saucers begin to show in the road they 
should be corrected immediately, provided the moisture 



484 



conditions permit of doing t^n, l)nr mi the earth roads the 
soil may he either too wet or too drv to aUow tliis to he 
done well, and the hiiiliest success will he nttaincd when the 
road mastei' comes to know and understand his conditions 
and tlien is alert to uionc ;it just the I'iulit time. The rnts 
will he formed chiefly in hotli the \-ery wet and the \-ery dry 
weatlier, and in I he c Mint r\- wle're spriiikliuii- the roads 
cannot he ail'or(le(l, cNcrythini:- must i)e );lanned to take ad- 
vantage of every shower heavy ('noiigh to hriiig the road 
into condition for working with grader, shovel, rake and 
roller. 




Fig. 233. 



- View oil tlie same road showiiis: the tool housi- where ajipliauces for 
carins for the road are kept. Photo, in 1895, near Grignou. 



The intelligent use (d' the grader and rolh'r at the right 
time after the rains of n wet period and after a dry period 
will make marvelous changes in the character of earth roads 
of all classes and particularly in those which are proverh- 
iallv had. 



485 

We cannot too strongly eni|)li;i.siz(' tliat to di-ivo up one 
side of the road with a road machine and l)ack on the other, 
scraping a lot of loose, heterogeneous rnl)l)ish and earth 
into the middle of th(i road, to he traui])ed out again by 
the ti'atiic, is neithei- re])airing nor maintaining the road. 
The material hrought upnn the road should he well dis- 
tributed and hari-owcil until an cs'cn, iinit'oi'iii layei* has 
been seciii'ed and tlicn the rdlei- should he thoroughly aj)- 
plicd when the earth is in jnst the I'iglit ('(mdition to ])ack 
well. AVork of this soi-t will count and will l)e appreciated. 
:30 



486 



METEOROLOGY. 



CHAPTEK XXII. 
THE ATMOSPHERE. 

As the life jn-ocesses of all ])lants and animals are de- 
pendent npon the air, and are greatly inflneneed by changes 
in it, it is eminently jtroper that the atmosphere and its 
changes slionld be considered in their relations to agricul- 
ture. From the standpoint of food su])ply the clover crop, 
for example, containing at maturity 70 per cent, of water, 
has — directly or indirectly — obtained all but its ash in- 
gredients from the atmosphere. The water is brought to 
the soil as rain, tlie carbon comes from the carbon dioxide 
and the nitrogen is obtained from the soil air by the free- 
nitrogen-tixing bacteria. Tlu^ rehitions stand 

Water from the atmosphere us rain 70 percent. 

Nitrogen from the soil-air 70 per cent. 

Carbon and oxygen Ironi liic atiiiosplierc a.s rain and carbon 

dioxide 26.57 per cent. 

Ash ingredient.s from the .<oil 2.78 per cent. 

Total 100.00 per cent. 

Thvis 117.27 i)er cent, of the ])laiit food is derived frcmi 
the constituents of the atmosphere, either directly or in- 
directly. 

604. Relation of the Atmosphere to the Earth.— The earth 

consists of three concentric spheres, (1) at the center, the 
solid, or earth-sphere ; (2) surrounding this is the liquid or 



48T 

\vatei'-s|)li(M'e, ( ;> ) and outside of all is the ojus or air 
sphere. These have been named — 

1. Geospliere. 

2. Hydrosphere. 

3. Atniesphere. 

605. Interpenetration of the Three Spheres. — The mate- 
rials of the three spheres are neitlier entirely separated from 
one another nor stationary. Beneath the oceans and be- 
neath the surface of the continents the solid earth is per- 
meated by water. Even nnder desert skies there may be 
wells and the soil contains moistnre. With the water, too, 
ii'oes more or less of aii" from the atmos])here; the fishes 
of the oceans and lakes hnd air to breathe Avherever they go 
and the spaces in rock and soil not occupied by water are 
tilled with air. Floating' in the water and drifting in the 
atmosphere even at great hights are solid })articles of silt 
and dust broken fi'oni the earth-sphere, and nowhere is air 
9o dry that it contains no moisture. 

Drifted by the currents of air and water on land and at 
sea solid jiarticles are continually being moved from place 
to place. The ^\'ater of the ocean, of the lakes or of the at- 
mosphere is never at rest, neither is that which has pene- 
trated the solid crust of the earth. So, too, the air of the 
atmos])here, of the water and of the soil is continually 
changing and upon the rate of these changes depends the 
well being of plant and animal life. 

608. Relation of the Life Zone to the Three Spheres. — The 
living forms of the earth make their homes in the bottom 
of the atmosphere and in the top of the water sphere or of 
the earth sphere. This relation is necessitated by the fact 
that all living forms derive their food from the air, from 
the water, and either from the earth or from other forms 
which take their ash ingredients from the earth. This re- 
lation is further necessitated by the fact that all living 
f(U-ms must dwell where they can have a certain amount of 
direct sunshine or else where they can live upon other 



488 

forms which depend upon it, for this is the moving power 
of the world and all life implies motion. Deep in the 
solid earth no life exists. In the greatest depths of the 
ocean, where the air changes are slow and where little or no 
light can come, life is nearly absent ; and high in the atmos- 
phere only latent forms of life, like the spores and germs 
of niierosco])ic forms are drifted by the winds. 

In brief the life zone is that portion of the three spheres 
where the largest aiiu)unt of suusliinc is transformed into 
heat motion and therefore Avhere there is tbe largest 
amonnt of energy available for the use of plants and ani- 
mals. 

607. Depth of the Atmosphere. — We are living at the bot- 
tom of an ocean of air whose de2)th is at present unknown. 
Judging from the rate of decrease of pressure, as measured 
by the barometer, its de])th woidd be placed at something 
less than 50 miles, for at 30 miles, could an instrument be 
placed at that level, it is calculated that its reading would 
be only .005 of an inch of mercury. Observations which 
have been made upon the hight at which shooting stars or 
meteors become visible shows that this is even more than 
100 miles and it is believed that these bodies become visible 
only after they have traversed enough of our atmosphere 
to develop sufficient heat by friction and compression to 
make them white-hot; and although the velocity of these- 
bodies is very great yet the upjier air is so rarified they 
must pass through great depths before sufficient heat can 
be developed to make them white-hot. From these consid- 
erations it appears likely that air may be found at hights 
even exceeding 500 miles. 

(608. Composition of the Atmosphere. — The air at differ- 
ent times and in different jdaces contains a great variety 
of gases and volatile products but there are certain con- 
stituents which are found everywhere in the explored reg- 
ions and in pretty constant ratios. These are, for dry air : 

1. Nitrogen, forming about 77.18 per cent, by volume. 



489 

2. Oxviieii, forming about 20.61 per cent, by volume. 
-'». Water vapor, foruiiiiii' :ibont 1.40 per cent, by vol- 

lllllC. 

4. Ariion, foriiiinii,' about .78 per cent, by volume. 

r>. ('arl)(>u dioxide, foniiiui;' about .03 per cent, by vol- 
ume, i 

Jlesides tliese iuiiredicuts there are usually present in the 
air small amounts of ammonia and of nitric acid, which 
are brought down with the rains to the extent of 3.37 
pounds ])er acre per annum at llothamatead, England; 
1.74 pounds at Lincoln, ISTew Zealand; and 3.77 pounds in 
the Barbadoes Islands. 

Oxygen often occurs in the allotropic form of ozone, 
which is much more active as an oxidizing agent than the 
ordinary condition. 

609. Materials Mechanically Suspended in the Atmos- 
phere. — In the gaseous body of the atmosphere there are 
always mechanically suspended varying amounts of solid 
and liquid particles and bodies. These are: 

1. Inorganic dust grains or soil particles. 

2. Organic dust fragments. 

3. ]\licroscopic geTms and spores. 

4. Pollen grains from various plants. 
.5. Snow or water crystals. 

6. Water particles in cloud forms. 



PARTS I'LAYKD I'.V Til t DIFFKKEiXT INGREDIENTS. 

The atmosphere as a whole, in its relation to living 
forms, plays the important function of an equalizer of tem- 
perature, preventing the occurrence of such excessively 
high and extremely low degrees as would otherwise be pro- 
duced when the sun is above or below the horizon. 

610. Oxygen — Oxygen is essential to both plants and 
animals, it l)eing indispensable to the activities of the proto- 



41) 

plasm of living cells, wlic'tlier tliis be in tlie root, stem or 
leaf of ])lants ov in the tissnes of animals, in the develop- 
ment of mnsoular and nerv(Mis energy large quantities are 
used by the animal kingdom, and other large volumes are 
used by man with fuel as a source of ]iower and heat. 

611. Nitrogen. — The nitrogen of the atmosphere is pri- 
marily the sonrce of all nitrogen com])ounds of living 
forms; and by its dilution ot" nil the other ingredients it 
modifies their phvsiological eflccts. 

612. Water. — Moisture in the ntuiosphere greatly influ- 
ences th(! tem])C'rature of the eartlTs surface, as it is very 
opaque to dark heat waves radiated back into space. The 
frosts forming under clear skies and the absence of them 
when the air is dani]) are evidence of this influence. But 
the chief function of water is found in its large movement 
to the land in the form of rain and snow and its return 
from the fields through springs and rivers to the seas. As 
it falls it is food for i)lants and drink for aninuils, as it re- 
turns it carries away soluble salts which, if left, would de- 
velop st(n-ile "alkiili" hinds. 

613. Dust. — The dust ])articles give to the skv its blue 
color and by their radiation of heat into space become cold 
centers u])on which moisture condenses and snow flakes 
form. In this wav they greatly influence the ])recipita- 
tion, making it less violent than it might othei'wise be. 

614. Carbon Dioxide.^ ('a rbon dioxide is the source of 
all the carb(»n entering into the constitution of the tissues 
of both ])lants and animals, and it is a constituent of the 
great majority of feeding stuffs and of most organic com- 
pounds. 

Froni recent investigations it is held that carbon dioxide 
plays an im])ortant ])art, with water, in lessening the 
transparency of the atmosphere to dark heat rays radiating 
from the earth into space, and in this way holds our tem- 



491 



peratiire much higher than it coiihl he with this gas absent; 
and Chamberlin has proposed tlie working hypothesis that 
long period changes in the amount of carbon dioxide in 
the atmosphere may be the cause of the recurrent glacial 
periods to which the earth has been subjected. 

615. Pressure of the Atmosphere. — The air, like all other 
substances, has weight, and this weight causes it to exert 
pressure proportional to the amount above a place. Its 
mean pressure at sea level is equal to 14.73 pounds per 
square incli. A cubic foot of air at this pressure and at a 
temperature of 62° F. weighs about .08 pounds, 100 cubic 
feet would weigh 8 i^ounds, and 10,000 cubic feet 807.28 
pounds. Tlie air of a stable 40x40 feet, 10 feet high, 
weighs a ton. 

As the hight increases above sea level tlie amount of air 
to exert pressure is less, the weight of a cubic foot becomes 
less and it is necessary to breathe a larger volume to supply 
the system witli the same amount of oxygen. In the next 
table are given in round nundjers the bights al)Ove the sea 
at which the pressure w^oukl fall from 30 to 16 inches and 
the higlit to which these pressures would sustain a column 
of water, could a perfect vacuum be maintained. 



Hifclit above sea level. 


Barometric pressure. 


Hight of water column. 





30 inches. 


34.0 feet. 


l,80()feet. 


28 " 


HI 7 " 


3,MJ0 " 


26 " 


Sti.4 " 


.'),9TO " 


24 " 


27.2 " 


8,200 " 


22 ' ' 


24.9 '• 


10, fiOO ' ' 


20 ' ' 


22.6 " 


13, 200 ' ' 


18 " 


20.4 " 


16,000 " 


16 " 


18.1 " 



616. Applications of Atmospheric Pressure. — The most 
general application of atmospheric pressure by the animal 
world is in bringing air into their respiratory organs. 
Where animals are constituted so as to take advantage of 
this, a reduction of pressure is made about the luiigs, as in 
raising the ribs and lowering the dia[)hragm, and throi the 
greater pressure of the air outside expands them and causes 
a fresh supply to enter and fill the space. 



402 

111 (Iriiikiiiii, Jiiid in sucking- ;iii!iii:ils hike adviintugo of 
the nil' pressure !<• |)erl'(»riii these ()|K'ral i<»iis, wliicli would 
he iiiipossihh' without the prtvssure, and dillicult wlierc the 
pressure is siiialk 

lu'cii ill eatiiiii', aiiiiiials witli lips mid cheeks take ad- 
vaiitaii;e ol" air pressui-e to I'orce the food from hetweon the 
teeth after it has heeii iiiastit^ateil, and a man would make 
awkward work ealiiiii for the tirst lime in a vacuum. 

In the einiiiiioii suction piiiiip and the siphon air [)rcs- 
811 re is an esseiit iai lactor, as it is in I he hiw pressure steam 
eniiine. 

All (tf the iiiacliines inxciited for niilkinji; cows develop 
a vaeuiini and (h peiid upon atmospheric pressure to force 
the milk from I he ii(hh'r. 

617. Temperature of the Atmosphere. Tlie air is warnuKl 
in three wavs: lirsl, and chiellv, hv coiilaci with the earth's 
surface and with solid ohjects upon it, tliis lieatiup; ii'iving 
rise to ascendiiii;- currents <d' warm and (h'sc(-iidin,ii' ones of 
C(dd air. Second, hv (hirk heat radiations outward, which 
are ahsorhe(| hv the atmosphere as water absorbs light. 
Tliird, hv absorption <d' the direct ravs from the sun on 
tlieir wav to the earth's suriace. 

When air (hsceiids from a higiier to a lower level the 
pressure upon it becomes ureater and its xobinie is reduced, 
'I'liis re(hictioii of volume causes it to have a hiii'lur tem- 
jieratiire, and so if the air rises it expands, and this expan- 
si(»n results in lowering the t('m])erature. A rise or fall 
of l(l(» feet causes a change of tem])erature of .55° F. in 
dry air. 

If drv air crosses a mountain range and falls 2,000 feet 
its teiii|)erat.ure is raised 11° F. 

WluMi moisture is condensed (U- frozen in the atmos- 
])here the air temperature is raised by the lieat generated 
during condensation. So, too, if water is evaporated in 
the air, or snow melts, the temperature falls. This is why 
th(^ weather is always warmer in winter when it snows, and 
cooler after showers. 



41) ;i 



ciiAnKr? xxTir. 

MOVEMENTS OF THE ATMOSPHERE. 

618. Primary Cause of "Winds. Winds ii.su;il]y ho^in in 
one of two \\;i\>, rci'i'<'-<'iit(''l in I'iii'. 2.'{4. In tlio lower 



.......\. 




m 




Vh.. '"A. I ii;i;.'|-:iiri ^ho \\ j ii lt I In- (iiiLrin nf wiiiil i]io\ I'lii'-fjl s. 

part <»f the fieni'f tlic white portion represents a region 
where the air is ex])andin^-. When thi.s oeenr.s the lower 
and heavier air is carried upward and hrought alongside 



494 

that which is lighter ; then because of the resulting unbal- 
anced pressure the air above flows over outward, as repre- 
sented by the upper arrows. But as soon as some air has 
left the expanding area the whole column is made lighter, 
while the shaded areas become heavier from the added 
amount, and there is an unbalanced condition through the 
whole hight. At the center there is an area of low pres- 
sure and around it one of high, hence the winds set inward 
from all sides at the surface and outward above, as shown 
by the arrows in the diagram, and we have what is called 
a cyclonic system of winds, where the currents are mov- 
ing inward toward a low pressure area below and outward 
above toward one that is higher. 

If the central area is one where the air is contracting and 
becoming denser then air will flow in upon it from above, 
as shown in the upper part of the diagram of Fig. 234. But 
as soon as air moves from the surrounding area upon the 
central one the inner region becomes a liigh area, where 
the greater pressure forces the air outward below and in- 
ward above. Such a wind system as this lias been named 
an anticyclone. 



GENERAL CIRCULATIOIN" OF THE ATMOSPHERE. 

619. The World System of Winds. — In the region of the 
equator, wliere the lioat is greatest, the air is continually 
expanding, and flowing toward the poles above ; this makes 
the pressure greater on either side, resulting in surface 
winds setting toward the equator, as represented in ver- 
tical section in Fig. 235, Avhicli it will be seen is essentially 
the cyclonic system of Fig. 234. Farther toward the poles 
on either side, where the overflowing air from the equator 
accumulates, a high pressure belt is developed, from under 
which part of the air flows toward the equator below and 
another toward the poles ; these are the tropical high pres- 
sure belts. 

At the poles, where the air is continually cooling, it is 



495 



steadily (Icsc'eiuliiin' and tlowino (Mitwanl hclow, maintain- 
ing an anti-evclonic svsteni of winds ]iko that of the upper 
part of Fig. 284. Between the high area at the poles and 
the tro|)i(*;iI high ])ressure belts, where the two systems of 



■<=5^->-t"^--., 




surface winds mci r, there is, in the judgment of Ferrel, a 
tendency to develop a third or ]jolar calm belt, over which 
the air rises to return as an upj^er current to the tropical 
<?alm l)elts, or else back again to the poles. 

620. Wind Zones — There is thus a tendency for the sur- 
face winds of the globe to divide into six zones, separated 
by five calm l)elts, — two troiHcal or trade wind zones, two 
temperate or anti-trade wiml zones and two polar zones, as 



496 

represented in Fig. 235. In the two tropical and two polar 
zones the wdnds move toward the equator, while in the two 
temperate zones they move away from the equator. 

Above the earth's surface the directions of the wind are 
the reverse of those found below, that is, over the tropics 
and in the polar regions the n])i)er winds move toward the 
poles, while over the temperate zones the uj^per winds are 
toward the equator. 

621. Direction of Wind Modified by Form and Rotation of 
the Earth. — The sha])e of the earth and its i-otation upon 
its axis greatly modify the direction of winds. The rota- 
tional velocity of the earth's surface at the equator is about 
1,000 miles })er hour toward the east. As the distance to- 
ward the poles increases the eastward velocity decreases. 
When tlieref(n-e air moves toward the poles it travels east- 
ward faster than the land it approaches and hence blows 
from a westerly toward an easterly direction. 

On the other hand air moving toward the ecpiator passes 
over land traveling eastward more rapidly than it does, and 
hence these winds fall behind and appear to blow from 
some easterly toward some westerly direction. 

The surface winds in the tropics and polar regions are 
northeast or southeast, according to which hemisphere 
they are in, while the u]->per winds of the same zones have 
the reverse direction. In the temperate zones the winds 
are southwest or northwest at the surface and northeast 
or southeast above, according as they are north or south 
of the equator. 

622. Character of the Winds. — Winds blowing toward 
the ('(juator or descending from the upper regions have a 
tendency to be dry and to maintain a clear sky. On the 
other hand winds moving toward the poles, or rising to 
greater altitudes, tend to become more and more nearly sat- 
urated with moisture and hence to produce cloudy skies 
and precii)itation. 

The reasons for these relations are found in the fact that 



41)7 

air rising' or moving toward tiie j)oles is i^assing to^vard a 
colder region. Lowering the temperature of the air, with- 
out changing the amount of moisture in it makes it more 
nearly saturated, while raising the temperature without 
changing the amount of moisture makes the air dryer. 

Besides this, air is cooled by expansion and warmed by 
compression, and on these accounts ascending currents tend, 
to heconic (huii]) and descending aii' more dry. 

623. Weather of the Wind Zones. — It will l)e evident 
from 622 that, so far as tlie worhl system of winds are not 
interfered with by local conditions, they must give to the 
countries over which they blow characteristic types of 
weather. Fnder the tro])ical high pressure calm belts, 
where the aii- is descending, and for a long distance to the 
south and a shorter one to the north, there must be a region 
of clear skies and dry weather, and it is under these two 
zones that the deserts of the world are found. 

In the polar regions also the cloudiness and ])recipita- 
tion are relatively small for the same reason. 

But at the equator, where large volumes of air are ris- 
ing into the upjier regions and after doing so pass toward 
the poles, the air having become very moist before rising, 
quickly becomes saturated and throws l)ack to the earth 
large amounts of rain. The heaviest rainfalls of the 
v.'orld ar(' mnU'r the equatorial calm belt of ascending cur- 
rents. 

In the two temperate zones also, where tlie winds cool 
as they move northward, frequent rains and showers and 
much cloudy weather are the rule. 

There is thus a tendency for the systems of world winds 
to develop three rainy or cloudy zones and four clear 
weather or dry zones. Tlie dry zones are under the tropics 
and about the ])oles ; the wet and cloudy zones are under the 
equator and l)etween the tropical and polar circles of both 
hemispheres. 

624. Shifting of the Zones. — Because the vertical rays 



498 

of the sun fall alternately 23^/2 degrees north and south 
of the equator, the regions of greatest heating must also 
move north and south with the aj)parent shifting of the 
sun, and this causes the equatorial and tropical calm belts 
to move north and south. As a result of this shifting there 
is a tendency to develop two rainy and two dry seasons each 
year in the regions over wliich tlie calm belts travel twice. 



CONTINENTAL WINDS. 

625. Continents Disturb the World System of Winds and 
Weather. — Tlie small s})ecitic lieat of the land, its opaque 
nature and the absence of currents of all kinds in it cause 
the land surface to warm rapidly in the day and during 
summer, and to cool rapidly at night and during the win- 
ter. On the other hand the transparency of the oceans, 
which allows the sunshine to be distributed through a great 
depth of water ; their high specitic heat and the horizontal 
and vertical currents to which they are subject, all con- 
spire to make the oceans, relative to the lands in the same 
latitude, wariu in winter and cool in summer. 

During the huig days of summer and short nights, in 
high latitudes, the land becomes much warmer than the 
water and tends to develop ascending currents and a low 
air pressure, causing the winds to tend to blow toward the 
land at the surface and away from the land above in sum- 
mer ; but in winter, when the nights are long and the days 
short, the ground becomes very cold and the air contracts, 
causing the upper air to blow in over the continents above, 
thus developing high pressure, which forces the surface 
Avinds to move from the land toward the ocean in winter. 

There is therefore a tendency for the weather of conti- 
nents to be rainy and cloudy in summer and dry and sunny 
in winter, and for the oceans to be dry and sunny in sum- 
mer and wet and cloudy in winter. This is a very for- 
tunate relation, because it diminishes the evaporation on 
the land and increases that on the ocean and thus makes 



490 

the rainfall heaviest at just the season when crops need 
most water. 

626. The World Winds of January. — The prevailing 
winds of the worhl, as tliey arc observed during the month 
of January, are represented in Fig. 236, the lines of black 
circles showing where the modified tropical high pressure 
calm belts are situateil, and the light circles showing wheTC 
the equatorial calm belt and other low pressure areas are. 

In the southern liemis]iliere, where it is summer, and 
where the amount of land is small compared with the 
watei", the tropical high pressure calm belt is crowded to- 
ward the ])ole on the land and the air is liea]3ed up on the 
water, and the arrows show that the wind blows toward 
the land ; l)ut in the northern hemisphere, Avhere it is win- 
ter, and where the amount of land is much larger, it is 
also drawn toward the poles by the extreme cold of the 
land, while a low area is formed over each of the northern 
oceans. The wind blows oif both continents onto the two 
oceans and there are ui)per currents tending toward the 
land from the low areas. 

The equatorial calm belt is farther south everywhere, 
but esjiecially so over South America and over Africa and 
Australia, where the land becomes warmest. 

627. World Winds in July. — At this time of the year, 
when the northern hemisphere has the vertical rays of the 
sun and the longest days, the large masses of laud have be- 
come over-heated, the equatorial calm belt has been drawn 
northward and expanded into wide continental low areas, 
<'row(ling the high pressure belt of the Tropic of Cancer 
upon the Atlantic and Pacific oceans, as represented in 
Fig. 237. The warm air rising over the continents and 
flowing over upon the oceans makes high pressure there 
and low pressure over the land, and this brings surface 
winds and moisture from the sea, giving rains to the land 
in the summer season. 



500 




501 




502 

South of the equator, where it is winter, the high pres- 
sure cabn belt has moved nearer the equator so that the air 
is bhiwing- olf the three continents and they are exjierienc- 
ing: their dry season. 

628. Monsoon "Winds. — Where the world syste-m of winds 
is so strongly influenced by the land areas as is the case 
notably in the region of the Indian Ocean they have been 
given the special name of monsoons, and these give to In- 
dia its rainy season, when they blow from the ocean, and 
its drv season, when thev blow fi'om the land. 



ORDINARY STORMS. 

Besides the world system of winds, wdiich have been de- 
scribed, and the continental winds with their intensified 
forms called monsoons, which change with the seasons, 
there are others of smaller magnitude and shorter duration 
which give rise to our ordinary storms and the still more 
local tornadoes and thunder storms which are associated 
with them. These are technically called cyclones or cy- 
clonic storms. 

629. Cyclones. — Most of the rainfall of temperate 
climates and much of that which falls between the tropics 
and the eqnatorial calm belt, occurs during the passage 
of these cyclonic systems of wind movement, represented 
in Figs. 288 and 239. 

In these winds the surface air moves sjjirally about a 
center, going to the east as it passes toward the poles and 
to the west of the center when it comes toward the equator. 
Air coming from the eastward of a cyclonic center always 
passes to the polar side, while that coming from the west 
always passes to the equatorial side. 

630. Cause of Wind Directions in Ordinary Storms. — The 
cause of the wind directions in ordinary storms is the same 



503 



as tliat of fho direction of tlic iiciu ral cartli ciirrents, that 
is,— the form and rotatiou of the eartli. As the air leaves 
the ecpiator it passes over land niovini;- eastward slower 
than it and hence ontruns, appearing to blow from the 




Fig. 23S. — DiM^T.-iin dl' surface winds in a typical cjcloiiy. (After Ferrel.> 

S. AV. toward the X. E. in the northern hemisphere, and 
from the X. W. toward the S. E. in the southern hemi- 
sphere. If it approaches the eqnator it travels over land 
moving eastward faster than it does and hence appears to 
come from the jST. E. in th(^ northern hemisphere and from 
the S. E. in the southern. 

Where the wind approaches the center from the east it 
can only do so by having its eastward motion with the earth 
made slower than the earth's surface in the same latitude; 



504: 



while if it upp roaches the center from the A\'est it can only 
do so by traveling eastward faster than the earth itself and 
these changes in velocity canse winds from the west to 
move toward the eqnator side of the storm center, while 
those from the east always go to the polar side. The effect 
is the same as would resnlt from checkinc; or increasing 




TTiG. 239. — T)in!ir.nu of ujipcr a\ iiulf; in :i i.\iiic;il (•ycloiic. (After Ferri'l.t 

the rate of rotation of the earth npon its axis. Making 
it rotate faster wonld throw the air and water also toward 
the equator, while slackening its speed would permit both 
air and water to move toward the poles. 



631. Progressive Movements of Storms. — Cyclonic storms 
in all parts of the woj-ld liaxc a progressive movement 



505 




500 

across the earth's surfjicc iiiid I lie licncriil dii-cction is that 
of tlu^ prcx'jiilini;- winds of the part of the earth in wliich 
they arc. Tliat is, in tlic Icniix-ratc zones lliev tend to 
move awaj from the ecpiator and towai'd the east, wliile in 
tlie tropical zones tliev tend to move toward the ecjuator 
and toward the west. 

632. Direction of Storms in the United States. In tlio 
great majoritv <»f cases the storms ol' the I'nited States 
travel fi'om some westerly towai'd some castci'ly ])oint and 
iho mean direction is a litth' noi'th of east. \'ery many 
of tliese storms t ra\cl lor a time I roni the nortliwest toward 
tlie southeast until they near the lon_i;t it nde of the Missis- 
sip|)i riv(M% when they scry ot'teii turn their course strouii,ly 
to tlie northeast, and Fig. 240 re|)resents the- courses of the 
storm cenlers as they traversed tli(> country duriiiii; IMarch, 
1900, there being 1 :'. of them in all. Wherever the storms 
of tli(^ United States originate or enter the territory tliey 
nearly all h^avc it by crossing the New Kngland states. 

633. Rate of Travel of Storms in the United States.— 
There is a x'cry wide range in tlie rate at which the storm 
centers progi'css across the I'nitfd States, hut the ax'crage 
is from 2(i to ;>0 miles ])er hour. The circdes in the paths 
of the scu'era! storm tracks in Kig. I'tO inarh the positions 
of the storm centers at intervals ol 1 2 hours. 

634. Diameters of Storms. — The diameter of thes(> cy- 
clonic wind systems in the I'liited States is generally from 
1,500 to 2,000 miles, the longest diameter being usually 
from the southwest to the northeast. A typical one of 
these storms is re])resente(l in Fig. 241, where the heavy 
lines are drawn through |)laces having the same weight of 
air above thc'On, while the dotted lines are lines of e(|iial 
tenip(M-ature. It will be seen that this wind system reaches 
from north of the Great Lakes to well into T'exas and from 
North Dakota to Tenncsssee. 



507 




635. Duration of Ordinary Storms. — Tlxi loiiofli of time 
one of the ovdiiinrv cvcliniic storms of IIk; atmosplierc lasts 
is very varisiMc In some cases tin v arc of l)iit a few days 
duration; at other times tiiey last I'oi- weeks toi^ctlicr and in 
that time travel lon<;' distances. 

It is common for them to cross tlie United States, the 
!N^orth Atlantic and the wiiole of Murope; and one, nnnsnal 
at least in the comph'teness of its i<iio\vn histoi-y, has hccni 
followed fi'om tlu; vicinity of the Philippine Islands, 
across the Pacific, across North Anu'rica and the Koi'th 
Atlantic; across Enrope aiul well on toward the central 
portion of Siberia, where hick of sufficient observations 
prevented foMowinu it farther. 



636. Relation of the Region of Precipitation to the Storm 
Center. — Tlic i-e<>ion o\'ei- which rain or snow falls dni'ing 



508 



the ])as:*ai;'(' of cyclones across the I7iiite<l States lies Tisii- 
ally ill advance of the central LOW, mneh as represented 
by the- beavilv shaded area in the diagram Fig. 242, and 
at a distance of 200 to 700 miles from the center. 

In this area the precipitation is most continnous and 
steady over the eastern and northern portion, where the 
snrface winds range from S. E. to JST. E. in direction. To 
the southeast and sonth of the low center, where the winds 
are S. and S. W., there is a general tendency for the pre- 
cipitation to occnr in the form of showers, to he more vio- 
lent in cliai-acter, and local rather than wide spread. 




torni .-irf:!. 



637. The Origin of Ordinary Storms. — There is as yet no 
general agreement among students of meteorology regard- 



500 

\\\iX the orii^iii (if cvcldiiic winds ;iii<l sloriiis, ^oiiic tliiiik- 
iiiii' tliitt tlic low ai'cjts arc primary and tliat the areas of 
lii£2,ii pressure resnlt from tiie overtiow of air froiii one or 
more of these wliicli o\-ei-lap ; while others maintain that 
tile liiiiii areas are pi-imary ami that the low areas are sec- 
ondary. At the ])resent time the former view is able to 
brinii' mnch the stronger evidence to its support, so far as 
the operation of well established physical principles are 
concerned, and, with some modifications, seems likely in 
the end to prevail. 



510 



CHAPTER XXIV. 
WEATHER CHANGES. 

The forecasting of weather changes from 24 to -56 hours 
in advance is based upon several well established facts: 
(1) Rainy or cloudy weather is usually associated with 
preas of low pressure, about which the winds move as rep- 
resented in Fig. 242. (2) Fair or clear weather is usu- 
ally associated with regions of high pressure. (3) Both 
low and high areas have prevailing dimensions and move 
in the United States from the Avest toward the east. 

If areas of low pressure always had the same diameter, 
and if they traveled at the same rate and in the same di- 
rection, it would be possible for anyone to forecast the 
weather changes with much certainty 12 to 36 hours in ad- 
vance. But with all the irregularity of form, dimension, 
intensity, rate and direction of motion, it is possible for 
even a local observer to form a rational judgment of the 
approach, time of arrival and passage of an ordinary 
storm. Indeed, it will seldom happen that a strongly de- 
veloped storm can approach a locality without giving sure 
signs of its coming 12 to 24 hours in advance. 

638. Prevailing Winds. — In the forecasting of weather 
changes it is im])ortant to have clearly in mind the direc- 
tion of the prevailing winds of the locality, or those which 
are not due to the storm whose approach is to be forecast. 

In most parts of the United States east of the Rocky 
Mountains the prevailing fair weather Avinds are from 
some westerly quarter and they should be the southwest 
winds of the general Avorld and continental system unless 
modified by local conditions, such as give rise to "land and 
sea breezes" or ''mountain and vnllcv Avinds." 



511 

639. Locating- the Storm Center. — When the; weuthcr has 
been for soiiu^ time fair and the ])rovailing winds are blow- 
ing', the tirst indieation of an approaching storm is nsually 
to be fonnd in the long tlircjid-likc or hair-like cnrved cir- 
rus clonds represented in the outer front side of Fig. 242. 
If these are seen strongly developed in any quarter of the 
sky it is usually true that a more or less strongly developed 
low area exists in that direction. 

If these a])pearances tirst develoj) to the east of a north 
and soutli line the tirst ])rol)ability is that this storm will 
not reach the observer l)ecause it is already past and trav- 
eling away from rather than toward the place. 

On the other hand if the cirrus clouds show themselves 
well develo])ed to the west of a nortli and soutli line, and 
especially if between the southwest and northwest, then a 
storm center is located where its future course may bring 
it over the locality. 

640. Change in Wind Direction. — If a storm is approach- 
ing from the westward in the direction of the cirrus clouds 
these will ad\'ance and in a few hours will overspread the 
sky, the wind will decrease and finally shift to a direction 
which will indicate the approach of the storm, and more 
definitely the direction of the low area from the observer. 

641. Direction of the Storm Center Indicated by the 
Wind. — When a storm has advanced far enough to give 
definite direction to the wind it is then possible to judge 
from this the location of the storm center. 

Standing with the back to the wind and extending the 
right arm directly in fr(»i)t, and the left arm at right angles 
to this, the storm center is usmilly in a direction somewhere 
between the two hands ; this will be clearly seen from a 
study of Fig. 242 and also of Fig. 241. 

It will sometimes lia])])en that winds blowing outward 
from a ITIGII, or region of heavy pressure which has 
passed to the eastward, may be mistaken for those due to 
an approadiing storm, because they are easterly, but the 



512 

cliarac'tev of the sky and tlie Aveatlicr, Avith experience, will 
nsnallv serve to distinguish these anticyclonic winds from 
those belonging to the cyclone or storm proper. 

642. Discovering the Course the Storm Is Traveling. — 

.Vfter having ohscrved the existence and direction of a 
storm center it is important to know whether it Avill pass 
to the north or south of the locality or whether it will move 
directly across it. This can be foretold by the changes in 
the direction of the wind. Referring again to Fig. 242 
it wdll be observed that if the storm center comes directly 
toward the observer the direction of the wind will hold 
steady in the S. E. until after the storm has passed, when 
it will shift abruptly to the X. W., as indicated by the ar- 
rows laid on the axis of the storm track. If, however, the 
storm center is passing considerably to the north of the ob- 
server the winds will shift toward the south, finally becom- 
ing S. W. But if the low area is passing to the south of 
the observer then the winds will shift around by the north, 
becoming finally IST. W. and then W. 

If the winds hold steady, or if they shift to the north, a 
ge-neral rain or snow may be expected, unless the storm 
center is too distant, but if it is shifting toward the south, 
showers, rather than widespread precipitation, may be an- 
ticipated. After watching the progress of storms during 
two or three months, comparing them with the daily 
weather maps, one becomes able to recognize with much 
certainty the ap]u-oach of all well marked storms and to 
forecast their course and the character of the weather 12 to 
24 hours in advance. Mistakes will occur, just as they do 
with the Weather Bureau expert having a much wider 
knowledge before him, but with a little experience the 
judgment becomes mncli more reliable than W(mld at first 
be expected. 

643. Temperature Changes Connected with Storms Dur- 
ing the colder ])(trtions of the year the temperature changes, 
which are associated with the progress of a storm across 



r)i8 

the coniitry, are often very marked. The i>('iu'ral rule is 
that with the approach of a storm the temperature rises 
above the normal for the place and season, if it is the cold 
part of the year, but after the storm passes the temperature 
falls below the avcrai>'e. 

The rise in temjierature is due to three causes: (1) The 
warming of the air l)v the heat due to the condensation of 
moisture ; ( 2 ) the checking of radiation by the moisture 
in the air ; ( :>) the imj)ortation of warmer air from farther 
south under the influence of the storm center. 

It was shown in (41) and (42) that the formation of a 
pound of water at i^l^*^ from a pound of steam at 212° is 
associated with the development of IMjO heat units, and the 
freezing of a pound of water is also associated with the ap- 
pearance of 142 heat units. When, therefore, a pound of 
snow forms in the air from a 2:)ound of water vai:)or there 
is imparted to the air in which this occurs 

9Gi; -h 142 = 1108 heat units 

and if snow enough falls to represent an inch of rain the 
heat produced in the air is at the rate of about 

62 4 

1,108 -— = 5701. G heat units 

per square foot of the surface upon which the snow falls. 
The warming of tlie atmosphere Avhen it snows heavily 
must be very considerable and this is why it is seldom more 
than a few degrees Ixdow freezing when a heavy snow is in 
progress. 

The low temperature following a storm is due to three 
chief causes : (1) The rapid loss of heat by radiation from 
the ground under the clear sky; (2) the descent of cold air 
from high altitudes; au<l ('-)) the importation of colder air 
from farther north under the influence of the storm center. 

If reference is made to Fig. 2-11, it will be seen that the 
southeast quadrant has a mean temperature of 59° F., 
while the northwest (piadraut has a mean tem]>ei'ature of 



514 

only 17° F., 42° colder. In the northwest HIGH there 
is a temperatnre of — 10° F., while to the east of the 
LOW, above 60°, or a difference of 70° F., and while a 
part of this difference is dne to difference of hititude, most 
of it is dne to the effect of the storm. 

644. Barometric Changes Connected with Storms. — Dnr- 

ing the progress of a storm across a given station the bar- 
ometer falls more or less gradually until the center has 
reached the place and then it begins to rise, and may con- 
tinue to do so nntil a pressure greater than is normal has 
been attained. The changes of tlie barometer, therefore, 
become indices of the approach, progress and passage of a 
storm, and so, too, in a less degree, may temperature 
changes also, during the winter. If the barometer falls 
faster than usual, if the wind velocity increases rapidly 
and rapid changes in the wind direction occur, the indica- 
tions are either that the storm center is approaching at a 
high rate of speed or that its diameter is small and he-nce 
that it is likely to arrive sooner after indications have de- 
velo])ed. 

645. Cold Waves. — Cold waves in the United States are 
usually the result of a strongly developed storm which has 
traversed somewhat slowly the southern and eastern states. 
When these conditions prevail a HIGH area with clear 
sky and descending cold air from above forms over Mani- 
toba, or the northern boundary of the United States, and 
the strongly developed LOW area, traveling slowly, sets 
this body of cold air in motion toward it, which often at- 
tains a velocity of 25 to 40 miles ])er hour. Under these 
conditions intense cold is rapidly transported southward 
and eastward with the speed of an express train, and occa- 
sionally temperatures even below zero are transported as 
far south as northern Alabama. 

Besides the extremely cold waves just referred to there 
are others more common, which are due principally to the 
first two causes named, and are usually coincident with the 



515 



IlKill areas, following tlicin in their course across tbe 
count rv. 

646. Forecasting^ Warm and Cold Weather. — Since 
stronii'lv developed storms tend to draw the air into them- 
selves across long distances, it is clear that when they pass 
to the south during the cold months of the year cold waves 
are likely to follow their passage. On the other hand, if 
the low area has passed to the north it can only bring air 
from the south northward, im])orting but little cold with 
it. To be able to forecast the path of a storm then is also 
lo Ix' al)le to forecast the tein]ierature changes which axe 
likcdy to follow. 

647. Long Warm and Dry Periods. — It frequently hap- 
}»ens that a series of storms follow along a single track, one 
after another for several w^eeks together, and Fig. 243 rep- 




Kkj. 240. — Clinrt showing; coiiiliiioiis which deteniiiue dry weather in the 
eastern I'nited States. 



resents one of these sets of conditions. During the montli 
of October, 18J)5, all but four of the fifteen low areas re- 



516 



corded by tlie Weatlier Bureau, moved along axes within 
the northern belt marked "axis of low areas." 

It is clear that so long as such conditions as these pre- 
vail but little rain could fall in the United States, and all 
the northern portion must have unusually warm weather. 
The weather must be clear and dry because along the axis 
of high pressure the air is descending from the higher al- 
titudes where it is already dry, and in descending must 
become still dryer because of increasing temperature due 
to compression. As this is the air which must be drawn 
toward the low areas on either side of the axis it could con- 
tribute but little moisture for rainfall in either system of 
lows, and the map shows that but little fell. 




Fii;. 244.— I'atli of the West Indian JUu-rii-uie of Sept. 1-11, 1900. 



So long as a high pressure occupies the Gulf and At- 
lantic states, this effectually shuts off the moist gulf and 
ocean air and forces the storm centers to maintain a high 
•northerly course. Then, too, as long as storms pursue a 



51' 



course oif the Atlantic honler tliey also must shut oii* the 
moisture from the northern states and tend to inaiutaiu 
warm, dry weather there. 

Whether in this case the two systems of h)\v areas were 
the cause of the belt of hii>h ])ressure which ])revaile'd, or 
whether the high pressni-e belt simply nuirks the place 
where, for some reason, the upper air from the general 
wind system was falling to the earth, the outcome, so far 
as the weather is concerned, must be essentially the same. 

648. Tropical Cyclones. — During the latter part of Aug- 
ust, September and the fore part of October it frequently 
hap])ens that storms of unusual magnitude, intensity and 
destructiveness originate in the north tropical zone of trade 
winds, somewhere in or to the east of the Carribean Isl- 
ands and, after traveling westward with the prevailing 




Ki<;. 245. — I'ath nl' West IihIkiii llurricaiic of Aim'. 7 -H. 1.S99. 



winds of that zone, they tiiially make their way northward 
across the tropical calm l)elt and break into the zone of 
j!outhwest winds, making their way northward and east- 
ward, as represented by the two storm tracks in Figs. 244 
and 24.5, the former being the storm which ])roduced the 
terrible destructi(m of life and ])ropertv at Galv(^ston on 
32 



518 

September 8, 1900, when more than 5,000 human lives 
and $20,000,000 of property were lost. 

The severe cold winds which are designated as the 
"Northers of Texas" owe their origin to storm centers of 
iinusnal intensity off the Gulf coast, which set large bodies 
of air in motion from the nortliward, drawing it into them- 
selves as thev pass along to the southward and eastward. 



TIIUiSrUER STORMS, HAIL STORMS AND TORNADOES. 

Associated witli the ordinary storms which have been 
described in a preceding section there are others much 
more local in their character, shorter in duration, but often 
more violent in wind movement and precipitation. These 
are thunder storms, hail storms and tornadoes. 

649. Relation of Tornadoes and Thunder Showers to Ordi- 
nary Storms. — ( 'areful study of the time of occurrence and 
distribution of these storms has shown that they are almost 
always associated in a definite way with some cyclonic 
wind movement, and that they usually originate to the 
southeast, south or west of south of a storm center, in the 
region designated })v the cumulus clouds in the diagram, 
rig. 242. 

650. Tornadoes. — I'ornadoes are whirling winds of ex- 
treme violence which last but a short time, progressing al- 
most always from the southwest toward the northeast, often 
at the rate of a mile per minute, sweeping a belt 40 to 80 
rods wide and several miles long. Sometimes the width 
of the zone of destructive winds may reach a full mile. 
At the center of the tornado the moisture is swept together 
by the revolving winds into a dark funnel-shaped cloud, 
"where the velocity of the whirling air may be so great that 
few structures can withstand the enormous pressure they 
develop. 



519 




Fr.:. v4i,._i,i..,.,,,,„ .|,„wi,.^ ,1m. . ri^u, m , nrn,-i.lu,.s .-n,,! ilnunl.T stonii* 



520 

651. Schools of Tornadoes. — When the conditions are ex- 
tremely f;i\'ora!)]e for the formation of tornadoes they often 
appear in scliools, originatinii,' (uie after another or simul- 
taneonsly, as tlie main storm center progresses across the 
country, and Fig. 240 sliows how tliese local but violent 
storms are ndated to a storm center and how many may 
develop in the southeast quadrant as it travels along. In 
this figure the short, heavy straight lines to the southeast 
of the center represent the ])atlis of toi-nadocs which devel- 
oped during its course. 

652. Distribution of Thunder Showers. — Thunder show- 
ers, like tornadoes, originate in the gi'cat majority of cases 
to the southeast and south of a well develo]ied storm center 
and often large numbers of tlirin, scattered over consider- 
able areas, form as the storm progresses, much as is the 
case with tornadoes, and Fig. 247 is a diagram showing 
the advance of the front along which thunder showers orig- 
inated in a storm of early May, 1892, as recorded in the 
Monthly Weather Review of that month, p. 1-lS. 

On May 3 a long low area had advanced from the south 
and west and at 8 P. M. its lowest portion w^as central 
north of Lake Huron. The front of the thunder shower 
line had reached the east end of Lake Frie at 2 P. M. of 
the same date and showers Avere in jU'ogress along the line 
marked 2 P. M. in Fig. 247. As the storm center ad- 
vanced the thunder-shower-front also moved forward and 
swept across the state, as shown by the curves on the dia- 
gram, reaching Long Island at 2 A. M. on the morning of 
May 4th, the front thus progressing from 20 to 30 miles 
per hour. 

653. Conditions Under Which Thunder Showers and Tor- 
nadoes Originate. — In the diagram (»f Fig. 24G are repre- 
sented the wind directions and temperature relations which 
exist when conditions are favorable for the formation of 
both of these classes of storms. There is a region of warm 
moist southerlv winds to the south and east of the low area 



521 



and anotlior rciiidii of decidedly colder winds blowing 
fiMiii the west and nortli of west; and it is along the meet- 
ing of these two systems of winds that thnndeT showers 
tend specially to form, and in advance of it that the tor- 
nadoes have their birth. 



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Fic. 



-DiMfil-.-llll sli(i\\ili;i- tile 



(lc\cli)|illirlll (if thllllilrr 



654. Formation of Tornadoes. — The most satisfactory ex- 
}danation of the formation of tornadoes is represented in 
the lower portion of Fig. 246, which is a cross-section of 
the lower ])ortion of the atmosphere at right angles to the 
line dividing the two systems of winds shown in the upper 
portion of the same diagram. 

It is supposed that, nnder these conditions, the cold west 
and northwest winds at times over-rnn th(' moist warm and 
lighter sontherly stratum, thus producing a condition of 
unstable e(jnilibrium. When snch conditions have been 
developed the wai-ni air, at some point, is supposed to 
l)reak ^^) thi-ongh the over-rnnning colder layer, as shown 
in the lower rightdiand corner of the diaG:ram, and in do- 



522 



ing so is thrown into a rapidly wliirlino; niovenient in the 
same niamier that water rnns into whirls in discharging 
throngh the l)ottom of a wash-bowl. When the volumes of 
air w^hich must change places are large and the stratum 
of cold air deep, there comes ultimately to be developed 
an enormous rotary velocity which gives to the air an ex- 
tremely destructive power. 




Fig. 24ti.— IHiifii-aiii nl' the p.-itli of a toi-iiado. 



655. Explosive Violence of Tornadoes. — At the center of 
a tornado cloud the rapidly whirling motion reduces the 
air pressure at the center of the funnel so much as to pro- 
duce a high vacuum, and when a building lies in the path 
of the funnel the vacuvmi surrounds it so suddenly that 
often the great pressure of air within the building will 
throw the walls outward or lift the roof off before the air 
has time to escape into the vacuum formed by the tornado. 



523 



656. Unsteady Action of Tornadoes. — A tornado seldom 
displays a uniformly destrnetivc j)ow('r and oft(uitimes 
tlu:' point of the funnel fails to i-eaeli tlu; ground and con- 
siderable gaps are passed in the path where little damage is 
done. This unsteady action is often due to the slowing 
up of tlie rotary motion in the cloud due to the great fric- 
tion developed at the ground. .Vftcr withdrawing to the 
upper air the speed increases sufficiently to allow the fun- 
nel to grow to the surface again and resume the destructive 
work. 

When the funnel rt-aches the surface it does not always 
describe a straight path along the ground, but tends to 
cross and recross the main axis of movement. 



T7OT 




mmnrm mrnt 



+2 FEET ,NOTT0ai^. 
•i Oowr^oowN BUT 



'NOTroi^ : 30 '2.* 

I DOWN . 76 f f CT.FetT^FEe: 

|fTUB8lSH lOOwH 



,30UT H 3*De 



wira 



iouTiH 
SIOeI 



Fig. 2-49. — Diiigraiii slidwiiiii ilic r<ii,ir.\ nidvi'iiicnr of winds in a tmuado 



657. Character of the Tornado Path. — It is usually true 
that the path of a destructive tornado is not symmetrical, 
one side being wider than the other, as represented in Fig. 
24S, where it Avill be seen that the northwest side is nar- 
rower than the soutlieast side. Xot only is the zone of de- 
structive winds wider on the south side but that of the 
sensible winds is also. On account of this character of 
the tornado track it is clear tluit if one ha.^ an occasion to 
escape from an ordinary tornado, the shortest path would 



524 

lie to the northwest, at rig'lit angles to the line of progress. 
The evidences of a rotary motion of the air in a tornado 
are abundant and conclnsive, and in Fig. 24U are repre- 
sented some of these. 

658. Formation of Thunder Showers. — Thunder showers 
ap|)oar to have an origin similar to that of tornadoes, but 
evi(kMitly occur where there is less air to change places, and 
probably also where the de])th of tlie (werlving stratnm is 
less. Indeed, it appears very often, if not generally, true 
tliat a volnme of cold iK-avy air has dropjjed directly to 
the gTound and is moving Ixxlily against the warmer moist 
air, wliich it is forcing upward, as represented in the lower 
left-lKU'd corner of Fig. 240. The rapidly ascending 
Avarm moist air is cooled by (>x])ansion and by mixing with 
the cold air, thus giving rise to the heavy preci]>itation so 
often observed. 

The horizontal r<:>ning movement shown in the diagram 
is often \i<»lent enough and involves so great a hight in the 
atmosphere, that often raindro])s are carried round and 
round until they become very large before they are able to 
fall. If the vertical circulation reaches above the zone 
of freezing temperature the raindrops freeze, forming hail. 
These hail stones, in the most violent storms, are often 
■carried around Avitli such force and so many times that they 
become very large before they are able to overcome, by 
their weight, the velocity of the air, and fall to the ground. 






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